There's so many ways. It sounds like you've assumed that for her to die she needs to be beaten in a fight. You CAN do this, you just need to establish a bigger fish. For example, maybe the big bad has a bodyguard who's even STRONGER and has been built up over the story or some such.
However...
well ok, if it's 5-7x stronger than a human, think about what 5-7 buff dudes could lift. Eddie hall has a 500kg deadlift, and he BARELY got that bar up. If we set that as an upper limit, that gives us around 2500-3000kg for 5-7 Eddie hall's to lift. That's around half the mass of an elephant. So...