Voting Question: Who’s name goes on the title of a house bought on a Land Contract?

We bought our house on a LC in July 2010. We were suppose to refinance a year later but we were unable to do so. The seller agreed, verbally, to let us continue the LC until we could refinance. The seller died December 2011. Her son came to our house a couple weeks after she died and told us to buy the house or get out. Does he have the right to sell? Doesn’t the house have to go through Probate? When I looked up the title for the house online, the only names on the title are mine and my husband’s. Shouldn’t the sellers be on there too since the house is seller financed?
I should add that the seller inherited this house and no money is owed on it.
The sellers name is NOT on the deed or title. The only 2 names showing are mine and my husbands.