1) your father can remarry as he is legally divorced
2) you can't stop his remarriage
3) if it is your father self acquired property you and your brother can claim no share in said property
4) your mother can seek maintenance from her husband even after divorce
5) she can file domestic violence case against her ex husband in India and seek right to stay in her matrimonial home or alternative accommodation as even after divorce they continued to stay in same house as husband and wife
6) she can also seek injunction restraining her husband from selling the house