No spirits can stay once you speak the word of God and the blood of Jesus.

Most state regulations require a landlord to evict a hold over tenant if they do not leave voluntarily.You should not have agreed to allow them to stay beyond the end of their lease.

If she doesn't leave, begin eviction for a holdover where, in many jurisdictions is much easier to win a judgement than for non-payment or other lease violations (where they can just show up to court with the cash and they get to stay, despite your time and court costs).Also, it would be very helpful to us for you to put your RE market in your profile or at least in your post, because in this part of real estate, too, location matters. 

Her husband and father came to help her move and stayed a couple days.

I don't know why choose to stay in something that makes 8% so they can save taxes today that they are going to pay taxes on in the future (when they are in a higher bracket).

Stay firm on your requirements. 

Stay within a certain price point?

They may not mind, but I personally would be irritated if my rent stayed the same but an extra person got added into "my" personal space.  

And no, I am not staying there.

Stay with it