She has accepted an Unconditional if Firmed offer (for which the original offer was AAB, no specific requirement re subjects, so a B in the particular one she was worried about would have been okay), therefore not eligible for Adjustment, as no offer to exceed. She didn't apply anywhere that she hadn't visited and liked, so this was a strong contender anyway.
The other offer was ABB, but with a specific requirement of an A in the subject of concern.
(Interestingly, although UCAS appears to have the course in Clearing, searching via the university website suggests that it isn't. As this is the only course that might tempt her into Clearing, the dilemma may never become reality anyway).