How do kids get deceased fathers girlfriend to leave house they inherited so they can sell it?

My ex husband passed April 6, 2018 leaving a trust to his son and daughter including his home and 6 rental properties. He had a live-in girlfriend for the last 8 years but she never paid a penny in rent, in fact never worked. Now that the kids own the house they want to sell but the girlfriend won't leave. She says she has nowhere to go and no money. My son gave her the trailer , the pick up truck and anything else she wanted to sell or take but she's still there. How do they get her to move so they can clean up the property and sell?