Will mothers assests go to the father after her death?

If their mother has died and left everything to her husband, then their father can leave that property (which is now his property) to whomever he wishes.  There could be other reasons to contest the trust, but the fact that dad didn't provide for one or more of his children isn't enough, by itself, to warrant a contest.  If their mother left her property to her husband in trust, perhaps permitting her husband to use the property or receive income from it during his lifetime and then leaving the property to her children when he dies, dad would be powerless to change it. California has no law requiring a person to leave property to his or her children or any one of them. You need to get a copy of the trust (and any trust that mom may have done) and review it carefully to see whether dad received property outright or in a trust that is not revocable by him. If mom is still alive, she also can leave her property to whomever she chooses.  That ("her property") would include her separate property and her 1/2 interest in the community property of her marriage to dad.