Mental Harassment from Paternal Uncle

Hi, I hail from Maharashtra and am facing trouble from my paternal uncle. My father passed away when I was a kid. My mother raised me (single child) and took care of all my education and other expenses. My mother and me used to live in an ancestral home. One unit of which is legally on my father’s name and the other on my paternal uncle’s name. My paternal uncle is wrongfully accusing my mother of stealing valuables and other items from this house. For which he has no proof. He keeps sending derogatory messages and makes distress calls to us and that make us feel pressured. His language and tone is very derisive. He has accepted he is doing this to only cause mental harassment to my mother. I have a hunch he has an ulterior motive to swing the property unit on my father’s name to his as a compensation for all the items he claims have gone missing (for which there is utterly no proof that they even existed or if they did then that my mother stole them). What is the advisable next step here?