Death is sort of temporary. As long as you still got a body, someone can cast a revive/resurrection spell on you and you'll be good as new (there's even a business eluded to that does that, finding dead adventurers and reviving them).

Now the team needs to get to the dragon several floor below because if they don't, they can't save and resurrect the sister. You can't resurrect someone who's been completely digested and turned to crap.