Hi
The name Joanne in hebrew means ‘G-d is gracious’ so you could maybe follow up on a religious themed tattoo incoporating the theme.
As for other ideas what is it that signifies the most about your mother to you?
The easiest ay to get ideas is to do the following;
What one word best explains your mother and/or your feelings?
What is her favourite item/song/past time/flower?
What is the one thing taht you both really share or enjoy?
Once you have answered them the ideas will flow more easily.
Take care
Matthew