Daughter in law claiming father in law property

My brother passed away after an accident during treatment in hospital in 2017. His wife left him in the hospital without taking care of him. After he passed away she came back and now she is claiming my brother s share in property. we are four siblings two sisters both married and two brothers. Elder one passed in accident. My father passed away in 2003 and has a house on his name. He did not write any will to my mother. My mother has one plot on her name. My mother borrowed 25 lakhs for the treatment of my brother and she is repaying interest to that. My brothers wife is demanding share in the house and also in my mother property. She is not taking responsibility in 25 lakhs loan amount. She is getting benefit of widow pension and other relief funds. She wants to leave us and want to get marry again. Please advice what to do ? If she wants to go to court what will happen.