Regarding the options, there really is a lot that goes into the terms so just some feedback based on what you've said so far.  1.

Nice to meet everyone - just signed up to Bigger Pockets.I'm a Halifax-based commercial real estate agent (7 years and 350+ transactions) and investor, looking to connect and network with others in the area.

I'm based in California but looking at nearby states for rental opportunities.

ThanksThere's nothing wrong with a tenant requesting assistance as long as they are communicating with you and making the effort to keep up on rent and responsibilities. 

I'll maybe cash flow negative 100/month for a year based on Hud and housing authority rates.

Seek a landlord attorney in your area to draft the agreement based on your needs.

Andy, I'm sorry to hear that your going through this, I don't personally know anyone dealing with such difficult tenants, but do know several Brooklyn based land lords who got tenants out in order to do reno. or dramatically increase rent. 

Before I would provide any capital I would want to see an updated proforma based on current situation and interest rates remaining where they are for the next 36 months.

When they're done with your taxes you should meet with them to go over your return, ask any tax questions, discuss any advice they have based on the return they just prepared and share your plans for the next year so they can give you advice on them from a tax perspective. 

Buy props OOS like 100s of others do from CA, with 10% or better net caps, based on cash purchase.