My nani Killed by giving mental torch by my aunt( mamas wife)

My grand parents were mentally torched by by Mami. She use to should on them . Give them bad tasting food. My Nanaji passed away in Nov 18. Post that Madhu Bhargava started misbehaving with my Nani. She used to say give me money to make food for you. My Mama Dr Rajeev Bhargava is a handpicked husband. She told the maid we will neither let her live nor die. She use to give her old food and things which have turned rotten. Mami mama were living in my Nani and Nanajis house and taking away all pension money. We were suppose to get her here this March. She was waiting for us. Went my Nanaji passed away she would walk and bathe and use bathroom her self. Within this period of more than a year and half she was torched by Madhu Bhargava my Mami and she died with out food From the When she was taking her last breath she was put on the floor just to remove the mattress from below as the maid gad to leave. Using ny Nanaji s pension Her maids were paid and Mami took all the other by getting blank cheque signed Please tell me what can be done against Madhu Bhargava.