Harassment by daughter in law

Dear Experts, My mother a 56 year old widow is being harassed by her daughter in law. Both my mother and my sister in law live in the same house but on different floors. About 5 or so years back my brother tired off his daily fights with her left the family house and went to a different country. Since then he has not come back. He remarried and is now living with his other wife and has two kids with her. The first wife however blames my mother for my brothers actions. She constantly fights, swears and demands a monthly expense from my mother. My mother is retired and has no source of income other than her rental income which at times is not sufficient for her own monthly expenses. The house was built by my mother but she had registered it in my brothers name when it was built about 12/13 years back. My mother lives with my grandmother who is about 80 years old. My grandmother has stayed with us since my father died 20 years back. We have no support from my brother be it financially or emotionally. My mother has been paying for the first wife's some expenses and her sons all expenses including school fees, clothes and other expenses incurred for a child. Till now my mother had been putting up with fights for the sake of my nephew (first wife's son) but now she has had too much. The first wife constantly harasses my mother and threatens to file a police complaint and get her arrested for not giving her an expense each month. She alleges that since the house is in her husbands name she is the owner of the house and she can throw my mother out any time (even though my mother paid for the house to be built). This has caused a lot of mental stress and anxiety to my mother as she is even constantly scared that the daughter in law can hurt her physically one day. She as it is has a number of health problems and this is just worsening her health. I do not live in India and for the restrictions on the visa requirement of the country I reside in my mother can not come live with me permanently. Please advice what legal action can be taken to stop all this and what legal rights my mother has over the property and in general. Thanks in advance