Custody Of US Child By Indian Parents Living In US

My sister and her husband want to get divorce, they live in the US with H4 and H1B visa respectively. They have a child who is US born and has US citizenship. They got married in India and moved to the US. Where should they apply divorce and custody of their child. Which jurisdiction is more favorable for my sister US or India (she doesn't have a job and has suffered emotional abuse from her husband and in-laws). What happens if her husband applies for divorce and custody in US, can it be overridden by India's jurisdiction if my sister and child are in India.