Sounds like you dodged a bullet here, I'd be happy she's backing out now rather than a week after she was supposed to move in.

But do care a lot about low energy bills.

For the probably $10k+ needed to bring the mortgage current plus the apparently large amount of repairs required, a lease option would be possible, but who would invest all of that time, energy and money for a home they don't even own?  

That being said, if it were my property I would bite the bullet and find that dead rodent.

Which all takes a LOT of time and energy.

The memorandum (some use a letter of intent) approach is considered a "soft lease option" because the memorandum is generally a non-exclusive agreement that gives the seller the ability to walk away at any time if they choose to do so (even once you've spent all your time and energy finding a buyer and the seller decides to walk away at the last minute), but also gives you the ability to gain an assignable interest via the memorandum in a way that feels less scary to a seller (and generally you can structure the terms of the memorandum to have the rental payments begin the moment you assign, so you don't have to make payments while you're trying to find someone to assign to).You can also gain an assignable interest through a "hard lease option" that is exclusive between you and the seller, and will usually require you to start making payments at a specified date.

My wife and I are in the energy industry and love our jobs but recent market conditions have us wanting to hedge our income resources.To be honest, I don't have any aggressive or lofty goals at this time.  

I found out that their all products are energy star and BBB rated windows and Doors.

Ill save you the time and the bullet holes.

I am new to this game, but I am full of fresh ideas and energy.