Sister in law is threatening brother to commit suicide or to throw her 2 years daughter from terrace

My brother is .married from 5 years and had 2 year old daughter From day 1 of marriage she is demanding and had anger issues. From 5 years he was suffering and doing whatever she and her family says from buying vehicle for her to buying house to buying amenities and transferring 40 thousand every month to her account from his salary demands and endless. She never satisfies. The trigger point of stepping out is that she blame my father that he is touching her inappropriately and then turned her point that my father is giving body massage everyday. Her family abuses my parents and brother. She is so smart started recording like pushing her daughter and capturing video like my mother is beating her ...creating false evidence She is totally mentally sick and had an anger issues. She uses abusive languages and pushes parents. My parents stays in Ahmedabad and came to Hyderabad only once year of couple of months My parents are really scared and don't want to take any steps as they are afraid that she might blame father for rape and throw him into jail. Kindly help