Selling Real Estate Mortgage and Deed

We are working with a family that is preparing to put their property on the market for sale. Furthermore, the wife name is listed on both the deed and the mortgage. The husbands name is listed only on the mortgage. In this situation, since the husband name is not on the deed, is he allowed to try and sell the home for more than what is owed on the mortgage? From our understanding, he has no control over this property due to the fact that the deed does not list his name. Any final decisions will be left to the wife.

We want to make sure we have a full understanding of what powers the husband actually has in this specific situation.