It is important to consult with a legal professional or financial advisor to fully understand the implications of assuming the mortgage and how it may potentially affect your financial and legal responsibilities in the event of unforeseen circumstances such as her mother requiring care.

Off market deals can be a great source for potential properties.

With the tenant friendly courts in Denver it's probably not a bad idea to cut your losses and send them on their way with their $630 but just be sure to tell the whole truth and nothing but the truth when the next potential landlord calls you up for a rental history verification. 

Which is your choice, thank you for sharing what you have(shows you want to make changes), but in order to give a good assessment I’ll make some simple assumptions and ask you these simple questions; Do you have a personal budget?

Having a potentially higher earning job is a big benefit when it comes to REI.

Most are all local lenders from that state that's giving me loan terms.But on your terms itself, let's say the loan is for 800k-1million, the potential return from the property is close to 2x to potential mortgage, what rates are you current seeing in the market? 

Questions:- How/where do you source potential deals?

It's a bit lower than what you were getting, but it could save you the hassle of finding a new tenant and dealing with potential vacancy periods.

The utility company should also have contacted them (or you-both your names should be on the utilities when the house is vacant) to let you know about a potential leak. 

Inspections and a fair contractor should assist you in assessing the property.