How to protect an inter-caste couple from family threats?

A Maratha girl and a Mang boy are getting married, but the girl's family is using political influence to force her return. They are also making serious allegations against the boy, trying to get him jailed for a long period. They have even threatened to kill him in the future. How can I help them? Also, I would like to know the approximate legal fees for hiring an advocate in such cases.