How can I deal with my mother's constant accusations of theft?

Hello All, I just joined this site today in desperate need of advice.

Most of you on this page have elderly parents, my mom is 50 years of age, and this problem of accusing ppl of stealing has gotten my attention in such a way I can no longer look away. I want to seek out help for her. My mom has been accusing my siblings and random ppl whom she comes in contact with of stealing. this started off every blue moon when we were kids. granted my lil sis use to sneak and wear my moms clothes as a teenager, she did mines too. As the year progressed I would get calls of her telling me how my siblings were stealing from her. It then escalated to their friends. It got to the point she would call the cops on their friends. after my siblings had kids it progressed to the grand kids taking from her. I remember getting a call that my niece stole from her an my niece got a spanking and punishment. I felt horrible bc part of me knew that it wasn't the case. later she found the item that she insisted was stolen.

fast forward every one is adults and my my nieces and nephews are teenagers and it has gotten worse!! my mom shared an apt with my sisters both on separate occasions at one point bc of her wanting to be around the grand kids. She now lives alone, I thought since she was living by herself this time she couldn't possibly accuse someone of stealing. Boy was I wrong...She now accuse the maintenance guys and security guards of the building of going into her apt. She reported them to the building manger and then back tracked her statement to them a few days later. Today she called the cops and reported that some one came into her home and tried to take the chain off her door so she wouldn't be able to put it on the door. She remembered that she snatched the door with the chain on the door as she was leaving out. She didn't remember bc she hadn't been home for a few days. The cop asked her was she on medication bc she started telling him of the things she say they are stealing which are so , in my opinion stupid ,the police thought so too. The police then questioned the building mangers who told him some things about her. I am assuming they told him of her prior accusations. The police then radioed into the station to see if she made any prior calls,bc he now thinks she is crazy. Just a few days before Easter she accused my sister who came to visit her of stealing makeup from her. she called me and talked about my sister in such horrible ways and later told me the things that she said to her kids about her. MY mother has a beautiful spirit she is great but this problem of accusing ppl of stealing is messing up her relationships and at some point someone will start coming into her home bc she has already made a reputation for her self.

I don't know if this is a mental disease of some sort or if it is progressing Dementia or Alzheimer's. this has been around for years in our lives but never at this state.

What should I suggests she get Checked for?? or should she be seeking psychological help?? Is this short term memory? please give me answers someone please???!!!!!!!

I also want to add that she always finds what she say is stolen yet she keeps accusing. I tried telling her not to accuse someone give it a few days to see if she finds it.