So a player on our server nuked our base. She said she "hacked" our MFFS system. I need advice.

We did a rollback, and we're back to how the base was yesterday. What can we do to deny her the possibility of doing this again. We don't ban any items, I want this to be in the default config, and I want a way to stop any chance of her bypassing our MFFS system again.

Please give us some advice on what to do.

Edit: Ok, I might realise that my decision to ban her and nuke her base was maybe a "douchey" move. We tried talking to her but she refused to promise us to not do it again (we are 5 guys). So we voted if she could stay or not. All of us wanted her off the server. We are friends (over internet/minecraft, she's not an IRL friend). And we wanted her there, but only if she didn't destroy the world. We did tell her that she could not destroy the world. (And friends don't grief friends.) The entire situation is a bit complex, and I must apologize if I made a dumb and useless post.

-Adrian