1. You have stated that the house was gifted to your father by his 3 brothers. Who was the original purchase of the house prior to the gift deed being executed? If your grand mother was alive at the time of execution of gift deed did she also sign the gift deed?
2. Your father became the owner of the property after the gift deed was executed in his favour. He was the applicant for the loan which was applied to and sanctioned by the bank/financial institution. So EMIs had to be paid by him alone. Now if he stops paying the EMIs the bank will attach the property.
3. In terms of the gift deed executed by your father's brothers, your father is the owner of the house. He cannot force his brothers to contribute to the EMIs of the housing loan. Since your father's brothers are not contributing to the EMIs he can evict them from the property by filing a suit for eviction against them in the court. They need his permission to even live in the property of which he is the owner. This is the only legal remedy available to your father.
4. The brothers of your father may file a case for cancellation of the gift deed which they had made in favour of your father. However, they will be on a very sticky wicket in the court as they had executed the gift out of their free volition.