Mother of bride escort?

Not at all! I like the idea.

I would only have one person escort her. Usually it the closest male relative, but you could have her sister if she'd be more comfortable that way. For our wedding, my brother escorted my mom down the aisle since my dad was obviously escorting me and my brother-in-law escorted my mother-in-law down the aisle since she's divorced from the father-in-law.