What reaction does Diana have to returning home in Act 2, Scene 2? What song is sung?

In Act 2, Scene 2, Dan is bringing Diana home from the hospital who, at first, doesn't recognize Natalie, the house, its contents, or her life with her family, singing "Song of Forgetting," a lightly textured, haunting ballad. Diana joins the song, commenting that "Dr. Mitchell" said there might be some memory loss.