The rules for underage marriages in NC are here:
States N-O -- Marriage Laws in the US by Age -- U.S. Teen Marriage License Laws
If she was 16 or 17 at the time of marriage and lied about consent, it MAY be possible to get the marriage voided, however that is not listed as one of the reasons for voiding a marriage:
Marriage Annulment
If she was under 16, then the marriage is voidable, but that doesn't mean that she's not married. It means that she's married - until she can get a court to void the marriage.
Either way, it's probably easier and less expensive to get a divorce - especially since her only hope of an annulment would be admitting that she committed perjury (unless she was under 16 - in which case she can probably get an annulment without admitting perfury).