I am currently getting a divorce from my wife. Before my wife and I decided to file for a divorce this her mother in law moved in 4 months go after my wife and I had a baby. Now I want her mother in law to move out but she refuses. How do I get her out my house.

Is this your mother? Her mother in law would be your mother. Or do you mean her mother moved in?

With that said, you serve her with a formal eviction notice according to your local eviction laws.

"her mother in law". As J-9 noted, this would be your mother. MY mother in law?

Whose house is it? Isn't your wife on the deed? Please clarify whose mother this is. Are you and your wife still living in this house together?