I laughed out loud at this: "the house is his because he is the eldest." Is his name Prince Charles?

My two cents. Sorry but this sounds like you need to lawyer up. This raises multiple legal issues that will not be satisfactorily resolved on Reddit. Did her parents have wills? Was there a probate or administration of either of her parents' estates? What state is the property located in? Was the house in a trust? Why is your wife's name on the deed? If the parents passed away in 2020, why are their names still on the deed?

At some point, you may need to go to court to clear things up. Contact a local attorney who does work in probate and real estate.