Harassment From Daughter In Law

My mother aged about 75 years is being harrassed regularly by her elder daughter-in-law. The sole reason is that my mother receives a pension amount to the tune of Rs20000/- and she (in law) always asks for that. She is having Political background and always torture like anything. She abuses using obscene languages most of the time. My mother is a chronic Blood Pressure patient and her BP goes to a high level in such a scenario. In addition, my father is aged about 83 years and his health condition is in very weak condition. We have 3 brothers and 2 sisters, We 2 brothers are living in the same compound and parents are staying with me. So please suggest what action my mother will take against her elder daughter in law to save her life.