If I block someone on Facebook will they see?

[Adamsman]

My mother blocked a really obnoxious and mean person on Facebook recently. I don't know the woman she blocked very well and don't have her on my friends list. But, I was going to block her so she won't reach me to try and get info about my mother out of me but if she sees I have her blocked to then she is going to go crazy on me or my mother. If I block someone can they see in anyway I have blocked them? This lady my mother blocked seems to catch onto "who is doing what".