The problem is not that you can't save her but how it all works or in this case doesn't. You can literally TP there and clear all goblins and other enemies before she even leaves the druid grove.
But of course she still dies. Why? Simple it's just bad scripting - maybe it's not finsihed yet, no way to know.
Playtesting can poke holes into stories like this all the time.
The whole sequence doesn't react to players actions in the world. Not like it's the only case like that. More than one "quest" can be seen with problems like this.
Nothing new in Rpgs, holes like this show up even with the best of devs. Good news is, it can easily be fixed.
