She gave us her address and said it the scariest house on the block.

I would be willing to lay the ground work and producing the Yellow Letters.

You can always be extremely picky and be looking for the pet parents that show up with a microchipped pet, happy to provide you with up-to-date vet and vaccination records, letters of recommendation for their dog(s) and an offer to let you meet the animals. 

I was told by the property manager we can write a letter to the Association that will be given to counsel.  

Here is a good post by someone bombarded with "will you sell" emails, calls, texts and letters. 

You're working really hard to rationalize your profit.Again, the way to move forward is to run this by your broker - and maybe even by your local Realtor's board's legal counsel to be safe (assuming they'll answer that sort of thing - they may not)  If I were your broker (and I'm not), I'd want a very plainly worded letter, drafted by your attorney, signed and notarized by the Personal Representative of the estate and all of the heirs that the fair market value of the property is $100,000 and they are willing to accept $60,000 as a means of selling it quickly, and that they explicitly reject your recommendation of listing it on MLS for $80,000. 

Would you get a preapproval letter from your lender for a 16+ unit?

Whether that's in an ad description, direct mail letter, etc.

Write a strong-worded letter sent via email or mail and remind her that has violated the lease as it is and you can pursue eviction.

Currently, that should be the first stumbling block.