Family DV issues

My sister eloped and married my brother-in-law at 21 in 2013. She had just completed her Bachelor's degree. Brother-in-law, then 22, was a trainee in the Airforce, a Central government job. Due to financial instability, our mother convinced my sister to complete her Master's degree to secure a job. They have two daughters, aged 4 and 6. His job required frequent interstate transfers and he had financial commitments to his family, leading him to leave my sister and daughters at our parents' house often. He refused to provide for the children's expenses, so my parents support my sister and her kids financially and emotionally. He tortures my parents by creating public nuisances and physically assaults my sister. After almost 10 years, my sister started working at a bank in Belgaum, but he has issues with her job. He harasses her mentally, visiting her office, threatening her to quit, and accusing her of adultery. His father is mentally ill, addicted to alcohol, and has been admitted to Dharwad Mental Hospital twice. My sister feels unsafe living with his parents, especially without her mother-in-law, who is often away, leaving the father-in-law unattended. Now, my brother-in-law is forcing her to quit her job and move to his native village, which lacks schools and job opportunities, to take care of his parents without any help. My sister and parents do not want a separation, but can my sister apply for child care compensation while living separately, as she just started her job and cannot support the children's maintenance? Or is it best to go for separation. On what grounds she can apply for separation & manitenance for the kids