does usafrux have dominion of property after death of owner
The usufruct at civil law is simply a life estate which terminates at the death of the grantee, the property interest of which then reverts to the grantor.
Usufruct is the legal right to use and derive profit or benefit from property that belongs to another person, as long as the property is not damaged. You need to consult with an attorney in your jurisdiction to determine what the legal obligations are under your system of law.
I am guessing that your dad's house is in Louisiana. I would suggest that you contact a probate attorney for a full explanation. Usufruct means that your stepmother has the right to use and enjoy the home until she is deceased. However, she cannot sell it. When she dies, you will have full rights to the home.