Just give the old hag whatever the ancient version of cocaine was. She will feel young and full of energy for a couple hours and then hopefully die of a stroke.
Please author, you have been doing a stellar job so far. Anything but the stupidass sudden love rival that has no chance but will shit up the story with forced drama.
I'm gonna be optimistic and hope it's something else going on. I think this story has been well-thought enough to deserve that.