What document do I need to get for us to be able to sell the property?

My mother died last 2003 and my father died last 2010. Now my sisters and I want to sell the house and the lot but the title of the lot was still in my mother’s name (with my father's name as he was married to my mother). There are no document or any last will of testament from both of them. I would really appreciate all the help you can provide us.