How do I help my mom who is constantly misremembering what she owns and then blames the aide for taking things or lying to her?

I'm sure the aide is used to these accusations and knows how to distract your mother. If not, hire a new aide who's got experience with dementia.

I agree a low dose of Ativan to calm mom down is a good idea.

Also, give her a big box of things she can rummage thru to her hearts content. Rummaging can offer a measure of comfort for individuals with dementia, offering recognition of familiar objects and a way to find purpose and meaning.

Giving mom some small job like folding towels or sorting spools of thread may help her as well.

Good luck to you.

Anyone who works with elders will be VERY used to it, as it happens to them on a daily basis. As good as my own brother was throughout the dx. of Lewy's, as peaceable and loving, this paranoia of "MY LOST STUFF" occurred when he hid his money in a new and strange place and then forgot that he did.

So often did this happen with my partner's mother, accusing her long serving Wilma over and over of this and that, that now when either partner or I lose something we always giggle and say "Wilma took it".

There is no reasoning, and there is no argument with a disease like this. Simply express your sympathy with her and attempt to move on. When obsessive thinking and acting out becomes continuous speak with doctor about some try at low dose anti depressant. That can sometimes help a bit. But often doesn't.
At some point you will be left with choices about how long you can continue home care with someone who really needs several shifts of several people each to deal with the continuous problems this condition brings.

Good luck.

You cannot reason with someone who has dementia. She isn’t going to believe you when you say no one is taking her dolls because her dying brain believes the opposite.

Your moms brain is broken and I'm sure if her aide has worked with someone with dementia before they don't think twice about being accused of taking her things as sadly that often comes with the territory.
Have you tried taking pictures of her things, so that when she thinks something is missing you can show her the pictures to reassure her that they're still there?
That may or may not work, but the important thing for you to remember(since your brain isn't broken)is that your mom can't help what she says or does, and that things will only get worse as her dementia worsens.
So if her care is getting to be too much for you then it may be time to think about placing her in a memory care facility where you can get back to just being her daughter and advocate and not her stressed out caregiver.

Dementia and logical discussions are mutually exclusive. You can never convince your mom that she is wrong and nobody steals from her.

Below are two excerpts from my book "Dementia Care Companion"

Accusing Others of Theft
The patient may stash away items or give items away, and forgetting that they have done so, accuse others of stealing. They may gift a scarf to a relative, and upon seeing her wearing it a few days later, may accuse the recipient of theft and demand the scarf be returned. This behavior is common in dementia and a source of consternation by those who are unaware of the illness and the resulting behavior changes.
·        When the patient misplaces an item and accuses someone of theft, do not confirm or deny the alleged theft. You cannot convince them that they are mistaken. Instead, help them find the missing item.
·        When the patient demands the return of an item, such as a gifted scarf, return it. Alternatively, avoid the problem by never wearing the item in the presence of the patient. 

Hoarding
Hoarding is most commonly seen in Alzheimer’s disease, frontotemporal dementia, and Lewy body dementia. Around 23 percent of dementia patients develop hoarding behavior, typically in the early and middle stages of their illness.
Patients hoard all kinds of stuff. They collect, organize, fold and package them, put them away in nooks and crannies, and then spend many busy hours searching in various drawers, cabinets, and wardrobes to rediscover and unpack the items, only to repackage and store them again.
Hoarding typically occurs in tandem with obsessive-compulsive behavior, overeating, and pilfering. What all these behaviors have in common is an underlying sense of anxiety, impairment in impulse control, and memory loss. The patient is trying to get a grip on a life that is increasingly out of their control, with a mind that is no longer able to hold on.
Hoarding is also seen in some older individuals who do not have dementia. Hoarding in older individuals may be a precursor to dementia and a warning sign.
How to Handle Hoarding
Although hoarding can be challenging for the caregiver, it does not help to get angry or scold the patient. Patience, creativity, and humor are better ways of handling all kinds of behavioral problems, and hoarding is no exception.
·        Find out what drives the hoarding behavior and try to remove the cause. Is the patient worried that their stuff may get lost or stolen? When they spread, repackage, and store items, are they trying to reassure themselves that they can find the items again? Are they bored from inactivity and a lack of meaningful involvement with the daily household affairs?
·        What do they collect and where do they store them? Are the collected items perishable? Are they valuable? By knowing the types of items that the patient likes to collect and where they stash them, you can better decide your next steps.
·        Reduce the number of drawers and wardrobes that the patient uses. Label drawers to clearly show what’s inside. You can write “socks,” “underwear,” etc. on sticky notes, then attach the notes to drawers. Or, you can affix pictures to drawers, indicating their contents.
·        Make life easy for the patient. Use a large plastic basket for the collected items so the patient can easily find them in one place and pack them again when finished.
·        If a particular type of hoarding does not pose a hazard, let it be. But, if the hoarding creates risks, such as food that spoils or clutter that presents a fall hazard, find ways to remove the risk.
·        Avoid removing or discarding hoarded items as this may add to the patient’s anxiety. Find other ways to remove any risks. For example, if hoarded food has spoiled, replace it with fresh food.
·        The patient may agree to donate some of the items to charity. Take this opportunity to quickly

My go to solution is always
Meet them where they're at. I had a client who sometimes believed that her parents were there with her, sometimes her brother, or "the kids" I would comment about their welfare and follow up with distract and refocus.
If she was focused on her Things we could discuss the items. No shame or guilt attached as her brain probably doesn't understand those things. But she will definately pick on the emotions attached to those.

Ask her Neurologist if there is any medication because this behaviour causes anxiety.

This is a common delusion among people with dementia. My mother and aunt experienced the same thing, although they did not yell at their aids. With my Mom's glasses, they would disappear. I'd find them in odd places; clearly she did not remember putting them there. My aunt used to stash away money in pockets of her clothes in the closet and in her laundry basket! There is not much you can do to logically explain to your Mom that nothing was stolen. However, it is a good policy to lock up valuables and financial papers when there are "strangers" in the house. Sometimes things do get stolen. Maybe help her take an inventory of the dolls and other valuables, and when she thinks one is missing go over the dolls and the list with her. Offer to put them in a safe place with a lock, where only she (and you) have a key to get at them. We bought my mother a filing cabinet with a lock for her financial papers and other valuables (her purse and important papers). Better still, if you haven't done it already, set up financial accounts with online access and go paperless. With delusions, it's best to respect the delusion and play along with it by helping her look for it or check the inventory, or try re-directing her thoughts to something else.

I would show some empathy but at the same time ignore it. I would find myself getting frazzled by trying to handle other household items and job tasks and would stop to listen to the rantings and ravings of a senior making accusations that I stole items. One time I was getting ready to leave my shift for that evening and was blocked by one senior with her walker having a sundowning episode. It was a horrible experience. I stood there on the step until she finally moved. My cell phone had died, so I couldn't call anyone to come and calm the situation down. She had a male cousin with a very gentle demeanor who could calm the situation down with her. I was trying to finish up her laundry before I left for the evening.

You can try, and I mean try, to meet them at their level, but after awhile, you crave the company of sane people to be around. Some of these people can be impossible to deal with, and no amount of redirecting or any other techniques would work when a seniors gets stuck in a loop. Sometimes family members are in denial about their loved ones and this person may need a higher level of care beyond home care.

There is nothing worse than harassing an overworked, underpaid aide doing a thankless job for these seniors. Our time and energy is stretched to the max and sometimes to the point of ignoring our own families and health needs to attend to others.

Aides get blamed for everything by seniors and sometimes well meaning family members. This is the worst of the worst I'm describing. Aides can only do but so much, and once a senior gets in their mind to target an aide or a certain family member, that's it. You may want to try another aide or that particular family member can pass the baton to another caregiver.

However, we have to greet these folks with smiling faces and a willing spirit of helping.

Aides keep up front that being dismissed from an assignment has nothing to do with our abilities to care for people with dementia, but a senior or family having a certain preference of another aide or family member, and that's okay.

That has to be so upsetting for your mom. Would it work if you were to tell her you’ve been taking a few dolls at a time to wash their clothes and do their hair? Tell her you will bring this batch back when they’re refreshed and exchange them for another batch.