Elderly Parent - where to start?

Where to start?

Location: NY state. My 85 year old mother lives alone and until recently has been fine mentally. We got a letter in the mail that she's borrowed money against her paid off house and it's in arrears about $20k and foreclosure proceedings on her house are underway. We asked her how much she's borrowed, when and for what she says she honestly doesn't remember much about it. She claims to have no paperwork. We had no idea any of this was going on. We take turns looking in her and try to keep her house in working order but it's still not in the greatest of shape. I'm sure it's not a romance scam or anything because she doesn't get out much and hardly ever uses a PC. She's very unhealthy with a ton of medical problems. Where do we even start with this? She has no money except SS and nobody else has the $$$ to bail her out. What do we do now?