So "Dem Babiez" are the only ones that can kill her.

So the only thing that has ever managed to stop this Siren, is a Bennett Witch, which as of Season 7 Finale/8 premiere no longer exists. (Bonnie's Cousin was murdered after putting the seal on the vault - STUPID- and Bonnie has no powers) The Vampires and everyone else can get body snatched, there is no other side, or NOLA other side, there are no more regents, the originals can get body jacked, Hope is... somewhere literally pooping her pants (so that's a no go) and not strong enough to do any kind of Strong permanent magic, Werewolves need not apply see:body jack, so the only ones that can seem to do any harm are "Dem Babiez," by sucking the magic right out the Siren and effectively killing her, because she's about what... A million give or take a few centuries, one touch and she's probably turn to old dust that dissipates before hitting the ground. However, why would that crazy lady want to kill the only beings on Earth that can stop the Siren, especially since she wants to defeat it, OH so Badly.