If they willingly converted to Islam, it should not be allowed to send them back to their parents to revert them back to Hinduism by force.
That is a hypothetical, as we are not sure of the details.
There needs to be some exception to the law for underage marriages, especially if there is the threat of abuse or violence from their families or other extraneous circumstances.
Saying that, if they were forced to become Muslim, these men and their supporters need to go to jail and these women need to go back to their families.