My Mother Is 83 Years Old. About Ten Years Ago

My mother is 83 years old. About ten years ago my siblings and I began to notice my mom acting out of her character. She would tell us stories that our step dad was doing mean things to her. Things like marking her clothes with blood or spotting her clothes with bleach and hiding her belongings or throwing them away. Our step dad was awnrey like that in a way so we didn't think too much about it. My step dad passed away about eight years ago. At that time I was out of a job and staying with a friend so I moved back home with my mom. During that time she began to accuse me of doing things to her and her things. She even accused me of stealing cans of green beans from her (I was in the process of moving into my own place)and that same day I had given her money to help pay for some groceries. After moving out she continued to accuse me of doing things to her. About 3 years ago she meet a man & remarried. Shortly after they married she began to tell us her new husband was doing mean things to her. She said he flirted with other women & never introduced her as his wife. That he was destroying things that were hers and leaving clothes in the middle of the floor so she would trip on them and putting deer stink on her clothes, shoes and her hair brushes and combs. She said we couldn't imaging the mean things he did to her but she has no proof what so ever of any of it. She divorced him a year ago. I got to know her last husband and I just don't believe he did these things. He is very friendly with people not shy and knows everyone in the town they live in. My mom has always been a jeolous person. Now she lives alone he has remarried again. We thought maybe she could live in peace and she was good for about 6 months. She claimed he hated her so bad he would never leave her alone. We had security cameras installed outside her home and a security system put in her home. After living with her and experiencing first hand her accusations I have voiced my doubts to her by telling her there were other explanations for these things she thinks are happening to her. She has started telling us someone is doing things to her again. Still no proof any of us can see. But now she thinks her ex husband is paying me money to go in her house and put this yellow deer stink on her carpet and all over her cabinets and clothes. She is accusing me of taking paper towels and toilet paper from her. She bought a grandaughter a Christmas gift and told my sister she had better put it away so the younger kids wouldn't get it. Next thing we know she can't find it and accused me of taking it. Everything always happens to her after I have been there. Now almost a month after Christmas she tells my sister she found the gift. She has yet to tell me. Probably because she thinks I put it back. I would never in a million years do any thing to my mom to hurt her or take from her or destroy of hers ever. I have always been very close to my mom we are a very close family. I have even told my mom she needs help that these type of things happen to some people when the get old. She won't hear a word of it. She said she can't believe one of her kids hates her so bad they would do these things to her. Nothing I say to her convinces her how wrong she is. It is absolutely killing me and our relationship is suffering. Is there a medical word for what is going on with her? Where do we go from here? I can't enjoy what little time my mom has left. Mom has 5 siblings I am the middle child. I am the only one she is doing this too. It breaks my heart she is going through this anyway not to mention what it is doing to me.
Sincerely,
Lorella Marchman