Dear barlshwartz1
I looked up the Zohar Daf 79A, it does not say your claim that she should shave her head bald. It says she should cut the hair that grew during the time she was Nida. This does not mean to shave the head at all. Also it doesn’t say specifically which hair on the body needs to be cut. Simply it could mean other hair on the body but excluding the head. Also it could mean all the hair the entire body which no one does- at least who shave their head if they truly followed this zohar they would shave the entire body from head to toe.
Bottom line, there is no source in the zohar for a women to shave a head.