Given that Eirin is about to dissect her with a Scalpel, I don't see why she'd be asking her for help. たすける can mean "to spare one's life." Frankly, that makes infinite more sense. If I'm wrong feel free to change it back.
And if Kaguya's liver is taken out, then she is fu*ked. The main weak spot of those that drank the Hourai elixair is the liver where it is stuck in forever and is the only way to kill them.
Well, it would kill her, sure, but in no way would it prevent her from resurrecting. No matter what is done to her and Mokou, they will not stay dead. Even Remi's non-expert remark about Hourai livers didn't mention anything about permanently killing them.
