Grand Daughters custody to her mother

My father is taking care of my elder brother's daughter for last several years because my elder brother's wife had thrown her own daughter out of house. Now she has filed a complaint against my father against domestic violence as well as she has also written that my father had purposely grabbed her daughter. We live in Pune and my sister in law has filed a case in Aurangabad in Family Court, Session Court and case is going on for last three years. My father is a pensioner and is 86 year old and my father has to look after the girl who is now 17 year old. Family court has also given interim order to my father to pay Rs. 3000 per month to my sister in law. My brother is expired and my sister in law is already a mental patient but she is misguided and is using her female rights. We want to know following: 1. My father is senior citizen but he has to travel frequently to aurangbad can this be stopped. 2. How fast we can give back custody of the girl to her mother. My father is now unable to take care of this girl. 3. My father has never stayed with my elder brother's family hence how fast this case can be closed. 4. My father is a pensioner can law ask him to pay any money to my brother's wife. Does he has any mandatory to pay daughter in law at the age of 86.