This is a fairly easy question to answer. There’s only one rule when it come to picking the person who will stand next to you on your big day — ready for it?The Rule: Your Maid (or Matron of Honor) should be someone who you are close to, someone you trust, and someone you know you will be able to turn to for support in the future as well.
So, that said, there are no rules saying that can’t be someone related to you. In many weddings, the bridal party includes siblings, so why not parents? I can’t say I’ve ever been to a wedding were the mother was in the wedding party, but I have been to two recently where the father served as Best Man. I think having your mother as your maid (matron) of honor is an amazing and wonderful idea that will be a cherished, lasting memory for both of you!
One suggestion I’d have, though, is to arrange for your mother to wear a different color or style then the rest of the bridesmaids (if you have more). This will help separate your mother from the other bridesmaids, so that she maintains a place of extra honor: after all — she’s more then just a Maid of Honor!