You can help her submit DMCA takedown requests. You can read how to do so in
this thread. The DMCA is a good concept, but the way it's applied by Google is total B.S. Not only are the videos/pictures NOT taken down from the sites they're uploaded to, but Google submits all the information in your request to the Lumen database and includes a link to it for everyone to see, in the name of "transparency". If her videos are already out there, she's pretty much screwed. Most of these sites are registered in 19th world countries that don't comply with privacy laws, and are protected by cloudflare, so you can't even find the host service to file a complaint with THEM.
Even if you've submitted the takedown requests, if someone knows your nickname and googles it in quotes, they might not find your videos/pictures with 1 click... But they will after 2 clicks, because the links to the DMCA takedown requests pop up right at the bottom of the search page. The Lumen database includes the exact links you requested to be removed, your name (at least you can use a fake one), as well as the reason for the removal.
What you can do to protect your identity is, obviously, remove ANY identifying information from your nickname, bio and physical appearance. If she's super-paranoid, she probably shouldn't be camming in the first place. If she's that scared that someone will find her, tell her to delete her account, pick a new vague username, never put her real date of birth or location on the cam site, learn how to use a VPN, block access to her country/region and disable the "appear on network sites" option to minimize the risk of getting auto-recorded. Tell her to wear a mask too if she's scared that she'll get found out, or just tell her to stop showing her face altogether.
Still, considering how much information cam sites collect on you, you're never in the clear unless you upload a fake ID and photoshop your face to a point where no future facial recognition software will be able to tell who you are.
Just look at how much Chaturbate collects on you. They store all the videos/pictures you upload, the IPs you log from, all the messages you send. I haven't heard of any camsite employees blackmailing broadcasters with the information they have on them, but that doesn't mean that it won't happen. We're humans after all.
So how to deal with this - either relax and be more careful, or stop doing it altogether.