Hey BP,I total newbie to the real estate investment world, and my two sisters have inherited our mothers house in Scottsdale, AZ very older neighborhood built in 1966, and is definitely a fixer upper pool is dead and empty, and 4 br 2 bth about 2300 SF. 

We have some short term rentals and are new travel nurses.

Without going through al the family drama, my wife’s mother was originally suppose to get it before an argument.

I'm still at home living with my mother and pay $250 /mo as my share for rent.

My mother in law currently rents her house and doesn’t have the credit or funds to buy, so I was thinking about buying a multi family and letting her live in one unit rent free assuming I could get an FHA loan.

I am legally blind, and my mother who will also live in the home, has poor health (she has a ton of stuff, and with her getting up there in age, I don't want to take the things that make her happy away from her). 

These bring in professors, nurses, doctors and employees year round. 

Or buy a 2/2 Condo....you and the spouse live there and you rent out the other bedroom to a traveling nurse.

I bought this home right before I went on maternity leave thinking I could rent the mother in law apartment in the basement to supplement my income while I am off from work.

Under Denver's Airbnb laws, those would be treated the same as any other kind of rental on the property where you live (whether that's a different kind of basement apartment/mother-in-law suite, a carriage house, or just a room rental STR).