Check on this site:
http://www.lpitr.state.sc.us/code/t20c001.htm
It outlines your States marriage laws. Unfortunately I can't find reference to "sees the error of her ways" as being a reason for getting an annulment but I may have missed something so please read it for yourself.
You mention that your friend is still young but I'm assuming she had reached the minimum legal age when she married - 16 years and there was a sworn affidavit signed by the father, mother, other relative, or guardian giving consent to the marriage.
Changing your mind isn't reason enough to have a marriage annulled - a lot of us would fit into that category! A lawyer is the best person to sort this out and as I mentioned in my earlier response, a lot do low or zero cost initial consultations.