There is nothing in the OP’s description to indicate his girlfriend’s first marriage was invalid as to form. She was a baptized Protestant who married a Hindu. The Church considers this a valid, though not sacramental, marriage. She should contact the pastor of their parish to discuss the possibility of beginning the process of obtaining a declaration of nullity.
This does not appear to be a lack of form situation; it would require a formal case, unless there is something significant missing from the OP’s post (such as his girlfriend or her husband being baptized Catholics).