How does selling to a house flipper work?

I think you are confused about what is happening here. You have inherited any equity from your mother in the house. You have also inherited any debts against it. To settle her estate you must refinance to get the bank to release the original deed of trust and have a clear title in your name. What the bank is doing is encouraging you to refinance to settle the chain of title for your benefit so you may properly inherit her equity. You stand to lose the equity if you do not. As for the flippers, all they are looking for is a good deal on the house. If you do not want to get a loan or cannot get one, it is time to put the house up for sale. I ume she named you as executor for her estate. If she died without a will then you have some more work to do. An estate attorney can help here. But to catch up her payments you must gain control of her checking account and start paying her bills asap. This may be a frustrating time but get going on it. Sorry about your loss.