Get the locks changed, get any missing items returned, cut off mom, and throw out/goodwill the new stuff.
A similar thing happened to a family friend but
1. The DH hadn't given his Mom the key she fooled the housesitter into letting her in as he left for work the last day of the couples vacation. (Said she was leaving groceries for them - housesitter as a 17 yo friend of the family)
2. Every picture of a "stranger" was removed from the house. Not just taken down, put away but she took them to her house to throw away. These were almost 100% pictures of the wife's family and friends including deceased family members.
3. Art that she had given them that had not been put up because of racist overtones was installed on their walls.
3. They got home, saw the damage, and the husband immediately called his mom and told her she had a hour to return the missing items are they were calling the cops and reporting her burglarizing their home. (Thankfully it garbage day was a couple days after this happened so the items could be returned)
4. The locks were changed. She was cut off.
I can see having a key to pick up the mail, take in the paper. People in my family don't have paper/mail stopped because 3 burglaries of family homes were traced to having the services stopped. Someone was either robbing home's themselves or selling the information depending on the incident.
(bolding mine above)
Thank you for sharing that story. I found it fascinating, for some reason. When I hear stories like that, I find myself wondering what in the world was the perpetrator thinking?
I can sort of follow the thinking behind, say, unpacking and putting away the plates and glasses in a kitchen, thinking that one was "helping" the new couple get their kitchen set up. (It would be wrong to do it without permission, but I can understand someone thinking, incorrectly, that that would be harmless and helpful.)
But I literally cannot even begin to understand the thinking behind removing pictures from the walls - and taking them away to be thrown in the garbage - as happened in your story above. (Yes, I believe you that it happened, it is just that I cannot understand how anyone, even a pushy person, could begin to justify that behavior in her own mind.) Good for the husband in the story for threatening to call the police, because it surely sounds like what the MIL did was stealing.
Your story happened to a friend of your family. If you have time, could you please tell us what happened to that family after that? Did you ever hear how the MIL tried to justify her behavior? (Did she attempt to explain it away?) Was she cut off for the rest of her life? If she was allowed back in to the lives of her son and DIL, did she change her behavior?