Was this an event or some such? I don't quite understand.

SPOILER (click to toggle)

You can select replacement limbs/body parts via the dropdown selections that will show up over your HA's usual limbs. I assume Rachelle set up shop during an early Survival event, but it was before my time so I don't know the full story behind it (she does offer human-colored limbs though which could potentially form a partial zombie skin coverup from before the days when they were removable skins)