Oh, that's wonderful news! [She smiles warmly at the other girl.] I'm so glad everything has turned out well for you. [You know, as well as it can when you're also trapped in a prison. Details.]
You don't have to thank me. It was really the least I could do. [Okay, she could have done less, but she likes to help. She wants people to be happy and feel welcome here so it can feel more like a home than a prison.]