Hey,

I don't think filling incorrect initial of your mother will cause you any problem at the time of counseling. These things are manageable at the time of counseling. That's why they do document verification to check the correct details.

Don't worry it's a very minute error. Plus you have given the correct initial in the admit card. At the time of counseling do inform them about it or rather mail them so that you will have a proof that your contacted them regarding the problem.

Hope that solves your concern.

Thank you.