Log IP Addresses?

[IvyKeepMommy]

I run a local Mommy Group, that has unfortunately been plagued with drama from one person who was upset that I set up a (better) competing group. My group is only open to members who live in our state (Maryland) and this person USED to be the admin of another group, but moved to North Carolina and isn't any more.

She's spent an inordinant amount of time coming up with schemes to spy on the site and harass members (emailing people to ask them why they are spending so much time, etc.) I've locked down a lot of things to prevent her from accessing the site, and recently discovered that she was logging in as another user (who does live in Maryland so can legitimately join). She was caught in the act with a screen shot and the member who shared her password was banned (after much discussion and even after being warned it continued to happen). I have blocked her IP address, but of course she can go to the local coffee shop and use their hotspot.

So.... Is there a way to block a regional IP address (i.e., everyone in North Carolina since really no one has a reason to be on my site from there) and if that isn't possible, is there a way to log in the IP addresses that members log in from? I have concerns about some of the members of the site who seemed to be friends with her, but haven't caught anything happening -- but this wench continues to email and call people with details of things from the site (because she's clearly bored and has NO life) just to stir up problems and drama.

Any other suggestions would be welcome!