But Meerna is nowhere to be found. Her brother is sad, kneeling by the lava. Wth.
Unlike many other "auto-deaths", this one I don't think you're meant to be able to prevent. Reason why I'm saying this is that there doesn't seem to be alternative dialogue or even a scenario where she doesn't die.
And the game usually has all those alternative versions covered... like for the dude being thrown to the spiders in the goblin-camp. Who *can* be saved (if you're quick enough) and I'm pretty sure he'll even thank you for saving his life. And that guy and his death are way more "obscure" than Meerna - took me two or three play-throughs to even realize he and his "death-scene" existed, while Meerna gets killed in a full-blown cut-scene.