A lot of things happened to Momo during the event thread. Among getting her cutie mark (which I haven't designed yet) she acquired some interesting accessories. Among them was a scarf from Silver Belle and a crown from princess Cadence. (Plus a flower crown form Hugo that she re-gifted to Silver Belle) I imagine Momo doesn't really wear the crown everywhere like she does the scarf though. Since the crown symbolizes a lot to her, she usually has it stored in a safe place.