My understanding is that the agent holding the listing agreement with the seller would be the one responsible for, among other duties, hosting the Open House.

Your only responsibility (and focus) is enforcing the lease.

You may feel you are the smartest kid on the block and that may even be true however, you cannot increase another person's risk and shed responsibility to another without their full awareness and acceptance and there are just too many holes in your permise which is why it is illegal. 

She sent me a response letter stating that she cant afford the $625 living on SS and that her son has moved out and to please work with her while she tries to find a new place. 

What would be a responsible term for a MF unit?

foundations SCARE people... its an emotional response. 

I did a "lease-option" with him where I essentially took over ownership and responsibility for the property as if I owned it.

You could probably double or triple your profit each month with a STR, but you would probably quadruple the amount of headaches and responsibilities.

Thank you so much for your response!

I get a much higher response rate when I'm directly calling them versus using a telemarketing service.