Domestic Violence

My sister has been married since [deleted], and in the initial days of marriage both in-laws and her husband very co-operative, but after some time she became ill and they have not taken care of her and even started torturing her mentally and physically. Her husband is male Nurse in govt hospital and father in law is principal in a govt. college. My sister given birth to baby boy and he died after 4 days of birth, and for that also her in-laws tortured her a lot. Our family is fully vegetarian and teetotaller but her in laws and husband used to take drink daily and they used to force her to clean meat and non-veg dishes. She was totally in depression and gone in mentally disorder. Her in-laws left my sister at my parents house after one and half year (after first child birth) that time she was pregnant and my father only taken care of her. She given birth to girl baby and she is still live and around 8 year old staying with her father and in-laws. Her in-laws left her at my parents house almost 3 year and after that they came with lots of family members and our common relatives to take her home back. Still my father send her back but they have not continued medicine and her in-laws started torturing her and see become further mentally disturbed and she got pregnant also in mean time for third time. Her in-laws and her husband never taken care even during third delivery time her mother-in-law and husband taken her to hospital by walk itself and on the way itself baby born and fallen. Due to that baby died and she had severe blood loss also. She got further mental disturbed also, and her in-laws not taken care of her even started torturing mentally and physically also. Now my sister staying with my parents since two and half year and they taken care very much, now she is fine. But now her husband don't want to take her back and even we also don't want to send her back but we would like to file DV case and criminal case. We want all to be behind bar and compensation to her. We have done expenditure in her marriage and medical treatment around Rs.12 Lakhs. So please advice whether my father can file case or my sister has to file case, since she may not reply to all questions since she is not recovered fully till now. And request suggestions what are document to make ready and whether we have to file case in court or police station. We want to file case for defamation also because her in-laws and husband spreading the word " PAGAL" for her everywhere. Please guide us also how they can be stopped in govt. job so that they will feel pain of my sister's mental harassment. Thank You very much in advance