What's a fair hourly rate?

A former boss, who I’m kinda friends with, recently asked if I’d be interested in doing some part-time work helping her organize some paperwork. I assume a lot of this is insurance stuff as she has a very sick child.

What’s fair compensation for a project like this? I don’t want to offend her by asking for too much—I’m sure she’d feel awkward negotiating—but I’m also pathetically poor and time is sort of a scarce commodity for me these days. We’re located in Orange County, California if it makes a difference.