Right before Zira loses her grip upon the cliff, we get a slight impression that maybe she's reconsidering Kiara's offer to help her but we can't really say for sure if she would have actually taken her up on it if she hadn't lost her footing. Of course, in the deleted ending of TLK2SP, it's pretty clear that Zira doesn't want to be saved. lol. I think Disney just chose to go with this type of ending, just to show that even the baddies can have a change of heart, even if it is too late.
I always thought there was a little part of Zira that was still good at heart anyways, proven mostly by how she reacts to Nuka's death, but that's just my theory. ^^