The house is habitable and in good to excellent condition. 

If they are drug addicts i would expect they would jump at some decent cash to fuel their habit. 

@Ray Reed Having heart and being very considerate is also a bad habit for myself as well.

Be consistent with your habit and continue to call.

Your hygiene and physical health are the first impression people get of you and it's the physical manifestation of your thoughts and habits.

Build good money habits if you don't have them already and your first deal I recommend it being a house hack. 

We don’t know any PMCs to recommend in the area mentioned, but since selecting the wrong PMC is usually more harmful than selecting a bad tenant, you might want to read our series about “How to Screen a PMC Better than a Tenant”:https://www.biggerpockets.com/member-blogs/3094/91877-how-to-screen-a-pmc-better-than-a-tenant-part-1-services-and-processesWe recommend you get management contracts from several PMCs and compare the services they cover and, more importantly, what they each DO NOT cover.

These are the situations in which you may add multiple ADUs:-Multifamily property (incl duplexes) in CA -- up to two detached ADUs, plus unlimited conversions of existing non-habitable space-City of San Diego -- outside transit priority area (TPA), you can build one additional affordable ADU and one unrestricted ADU (in addition to the 1 ADU on single family or 2 ADUs on multifamily).

. - Since you already have $30k stashed away, I would guess that you've already developed some great habits around creating a budget and sticking to it.

It's usually just bad habits on the tenants part and no amount of rental assistance will fix that.