Kaya crept down and checked tonight. Cheryl's not there and most of the people are dead, or close to it. Still, going to keep an eye on them from here a little longer.”— Manny Koch
Kaya was a member of the search party that was searching for Cheryl.
Since there is no Kaya either in Canterbury Commons or anywhere else in the game, it is plausible to assume that she died while she made her way back to Canterbury.
Kaya is mentioned only in Fallout 3.