You can't save her. It's her destiny to die.
God wills it!
Hahaha yes. The mages will it.
As said above, cant save her... you are bound to loose everyone you love... because as we know, Bioware are cold heartless douches. lol
Luckily you still have bethany/carver (unless (s)he died in deep roads bc you did not take anders)
I think its a plot point to make you hate the mages...
Luck me still have Bethany .