One for her to sign (if you're hand delivering) that acknowledges the receipt of the letter, and one for her to keep a copy of.Source: I'm a MA landlord and have gone through this process before.

In the letter I would also memorialize the dates and times you have previously spoken about this issue to her.This is a very direct way of handling this, but it sounds like your patience is gone and diplomatic means have not yielded satisfactory results.Also, a nice load of gravel that gets delivered and dumped right behind her car whilst parked there might also make a fun story to tell at parties...

If Buyer determines, in Buyer’s sole discretion, that the Property is not acceptable to Buyer, Buyer may terminate this Contract by delivering written notice of such election to Seller prior to expiration of Inspection Period.

“January appears to have delivered a perfect economic storm of sorts, with some consumers focused on paying off holiday credit card bills, others concerned about the recent bump in mortgage rates and still others that may have felt the squeeze from the partial government shutdown,” said HAR Chair Shannon Cobb Evans with Heritage Texas Properties.

One idea I have is: when I deliver my offer tomorrow, see what the seller says.

After you review these numbers you will be able to see if your goals are in line with what the market will deliver. 

If your lease agreement prohibits unauthorized occupants, you can deliver to her a 7 day notice to cure.

If the lines are communication are still open can you simply ask if you could collect their belongings and have them delivered to them at their new address?

@Roney Nakhoul what does the contract say regarding existing tenants and the condition of the property when delivered? 

@John BeckI hand deliver a letter and leave it in the door if nobody is home.