My daughter has purchased Apple Music and is a college student but I am getting charged $9.99 since she is on the family plan. I'd like to be refunded for the past purchases at the wrong price.

Who is the Family Organizer that is getting charged? I'm not sure the Family Organizer can get refunded if one member opts out for another plan. The Apple Music Family subscription is one price for all members (not per member). But I don't work for Apple, that's just my opinion. You can try:

Request a refund for apps or content that you bought from Apple - Apple Support