you are in a world where everyone is zombies but you can use the cure on one pony. and only have one cure you can use it on two options

Save rainbow dash. Attributes for rainbow dash if you save her : she has no back legs and can't fly but won't hold a grudge she can't walk good emotional support

Save Fluttershy Attributes for Fluttershy if you save her: holds a grudge doesn't know for how long and can go out and get supplies

They are both infected but you only can save one