Q. Must I inform my mother that I am giving her Zakat?

A. YOU CANNOT GIVE YOUR MOTHER, FATHER, GRANDPARENTS, AND ALL THOSE THAT GO UPWARDS ON THIS CHAIN, NOR CAN YOU GIVE CHILDREN, GRANDCHILDREN, GREAT GRAND CHILDREN AND ALL THOSE THAT COME DOWNWARDS ON THIS CHAIN YOUR ZAKAT!!!

You are welcome to give your zakat to uncles, cousins, neighbors, people in the path of Allah, orphans, the destitute, friends, etc. your Zakat, so long as they possess below the amount of Nisab.

Allah certainly knows best.