The only calls I've had from her were valid repair calls and once to apologize for a rather loud argument she had with her adult son that she thought I may have overheard.

Also the window must be large enough to serve as an emergency exit for a large size adult to fit through. 

He should be on the application as one of the adults living in the house.

Always screen every adult.

I was thinking of contacting APS (adult protective services) and schedule a Social Worker visit, but not sure if I need to work with Section 8 prior to doing something like that.Also, as much as I like the inherent security with Section 8 tenants, I cannot imagine how much of a nightmare it would be if I actually needed to take care of some administrative work, like follow-up on a failed inspection, or submit an annual rent increase, because the agency is so unresponsive.

or We do credit, eviction, and criminal background check, what issues might we find on that for you and the other adults who will live at the property?

like many i have in the day I was at the street level and actually talked to these folks one on one.. there are  wide variety of issues and stories.main ones are divorce.. loss of job  health garden variety mismanage. and some very sad ones the ones that really would get me is back in the pre 08 days you could have a 75 year old retire widow with her delightful adult children living in the home and talk her into refinancing it with a nija loan..

If so, the answer to your question appears to be in the instructions for that form:"As a landlord, you are required by law to provide one Certificate of Rent Paid (CRP) to each adult renter" So it appears you still need to give the tenant one since they're "an adult renter" (The PHA is not your renter.) 

Adult son stayed and needed more time to look for a place. 

They're adults.