At this point, your best bet is time - & open windows.

I'd say your best bet to pull out equity is a small, local bank. 

According to a recent #BloombergBusiness article (Starwood Bets $5.4 Billion that Apartment Rents will keep Rising, Oshrat Carmiel, October 27, 2015), Starwood’s CEO, Barry Sternlicht, indicated that the purchase decision was made not on the presumption of strong rental growth, but on a rent growth that is projected to increase just marginally over inflation.

(I bet it is the same roofer).Good luck with your leaks,

Your best bet is likely to be a hard money loan...in which case they would lend a percentage based of the value and repairs of the house, and you would need to come up with the other part of this...which I think most hard money lenders would be ok with that cash coming from your parents.  

More than the few hudred dollars for the lien I bet.  

Since you won this item on ebay for $250K I'd bet money its worth... $250K.

My bet is that both have to go.

If granny loses money you can bet you're getting some phone calls, regardless of the terms you devised you can end up in court very quickly. 

I too do SFR rental properties in SoCal ... most BP'ers assume that those will not be profitable in this market, but that has not been my experience, and I'd bet not your family's experience either :) Happy to network and exchange notes on REI anytime ...