How to get child back

My Friend Mr. MK gone to South Africa long back and obtained South Africa Citizenship. He Married an Indian woman Mrs. BK in 2012. Marriage taken place in India. After marriage she has gone to South Africa. She became African Green Card Holder. She is holding Indian Passport. They got one male child, present age 6 years born in South Africa. Child got South Africa Citizenship. Two months back, she came to India along with male child. While coming to India, she told that she would be back in a month and accordingly obtained No Objection Certificate from her Husband for the child [South African Citizen] travel to India. Now, she informed her husband that she would not go back to South Africa, wanted divorce and keep the child with her. Both Husband, Wife and Child are Hindu Religion. Now my friend is requesting her to come back to South Africa. If she is not interested / comfortable to go back to South Africa, he is requesting to send back the Child, who is South African citizenship. Please inform the options available to get the child back to South Africa from India. Kindly suggest the options available as per Indian Law.