If your grandfather is living then he will be the absolute owner of the house property where you live with your family members.
If your grandfather is not living, then this property shall devolve equally on all his legal heirs provided your grandfather is reported to have died intestate.
In that case your father is entitled to a legitimate share in the property.
If your father is medically proved that he is mentally challenged then you may apply for court guardian to take care of your father and his property.
After being appointed as court guardian, the guardian shall take care of the properties that belong to your mentally challenged father till his lifetime, after which the properties shall devolve equally on all his legal heirs.
Thus during the lifetime of your father, this property cannot belong to a third person, be it his children or wife or anyone.