Texas - Tenants Guest won't leave

[Grissel Garcia]

My Tenant's mother from out of town was supposed to visit him for a week. During the course of that week she decided to leave her husband and stay in Texas. She is now refusing to leave the property. My tenant, her son, has asked her repeatedly to move out and she doesn't. What actions can I take to force her to move out? I don't particularly want to remove my tenant as well, as he has otherwise been an exceptional tenant.