I feel sorry for what has happened to Marianne, but I don't think she should just quit altogether. I think she should stick around despite what's happened even though it could possibly happen again.
I think we all need to realize that stopping piracy completely is damn near impossible. That's like saying you want to completely eliminate crime and terrorism from the planet. It's something that will never happen.
I'm not saying we should sit back and not even try to stop it. But trying to stop every hacker and pirate out there can't be done. You'll always have some jackal doing something like this. The music industry can't stop every file-sharing website and the movie industry can't stop every bootlegger. You'll always have some crook sneaking around. Companies that do diamond and gold mining around the world know that they can't fully stop smuggling and learn to accept a small percentage of it.
So what should Marianne do? The only thing I can see is to either quit or just continue like normal and regularly check to see her security is tight. I don't know how successful you can be to try to trace the culprit here considering they can easily give a fake name, website and e-mail address. But at least looking up this stuff here can give you a shot at capturing them. I mean it's better than nothing.
There's not really much you can do in this situation even if your website is safe and secure. I do think that, like before, she should monitor what she posts here and at her site and post things at her discretion and check her security. I also think she should learn to accept a small percentage of piracy. I mean even the most safe and secure website can still get hacked here and there. If this is an isolated incident, then I don't think she should just throw in the towel. If this is something that is frequent, then she and her website people should really examine the security and fix things because a major problem is occuring.
In no way am I endorsing what has happened, but as I said, I do think we need to realize that stuff like this happens and it will continue to happen no matter what we do. You can't stop every hacker out there. It's just something that comes with the territory of making art for entertaining people. All Marianne can really do is just work on trying to stop the problem as much as she can even if she can't totally stop it.