My son and daughter-in-law are living in my house, which I own. Can they stay here without my permission? If not, how can I ask them to leave?

In India, you have the right to ask your son and daughter-in-law to leave your house if they are not tenants with a valid lease agreement. You can send them a notice to vacate, giving them a reasonable time to move out. If they refuse to leave, you can file a case in court for eviction.