I was told by the district's planner that a residential facility which houses 3-5 Unrelated adults is permitted in all districts except Limited 1 Family.

If this remains the case, what are her or her adult son's options if this remains the situation after his passing?

Between student loans, bills and just adulting, it would take me years to comfortably fund this investment.

Found 5 heroin dealers, 2 sexual predators, 2 violent felons and some prostitutes in the units. 

It seemed to me like a friendly group of people with similar goals and willing to share advice.I understand I'm an adult and I don't need my father's approval for something like this, but it's just very frustrating how resistant he was to the idea.

For millennials all they really need is a overstuffed couch and a web connection for their adult toys.I believe they make their income as professional bloggers.

You can't teach him how behave like a responsible adult, so conversation here will be unproductive.

we are a family of 5 (2 adults, 3 children) all healthy.

The wear and tear goes up with that many adults living in the house and everyone knows what goes on during flight school. 

I would contact the Dept. of Aging and Adult Services or Adult Protective Services or its equivalent in San Diego and report this situation.