The Book's ending (spoilers)
Is it true that the girls actually murnder fiamma with sticks
to anyone who's read the book would it have been a nastier ending and why do you think it wasn't used?
Yes.
Not sure why they changed the ending, perhaps they thought this would look better for the screen- more dramatic? They definitely took some liberties, changing where everything is set (from South Africa in the 1960s or so to London in the 1930s) and some other little things were tweaked.
Remember, remember, the Fifth of November...