Mental harassment by mother in law and husband

Hello sir/ma'am. my name is manav sharma. my sis got married 11 years ago. her husband and his mother there are three member in her family and ya one child. from beginning her husband don't do any work. and her mother in law retired from government job. she is getting two pensions. one and she got money from his husbands jobs he was also central government employee. my sisters husband was getting job behalf of his father. but his mother didn't helped him. from starting he do drink daily. but now he starting drink from morning till night. he wont to do any work for family. and his mother do support him. she is giving him money for drink. he have own car. his mother do all expenses for him. now there is problem is that my sister don't want to stay with them. she moved and came my parents house. my mother and father both are old and they cant afford. my nephew is very intelligent boy. for his study am worried. his father and his dadi not supporting him. even we went his school and asked for TC and migration but they said u have to pay four month fees which is pending. now his dadi said i will not do anything. and his father also said he dont knw anything. now everyone in tension what to do. we cant afford lawyer. as i know for this case court will take so much time. and they are harassing my sister very much. we are worried about child. have no idea what to do. we never saw court and police station. what to do please advice me.