There's not much at Fold3 for Frederick Callaway I'm afraid.
RE 23589, L/Cpl, single
death 17/9/1920 disease
Claimant mother, Mrs R Callaway,73 Payne Rd, Freemantle, Southampton, age 50
seems to be an award of 5 shillings.
The Callaway family is at 73 Paynes Road in 1921: Henry, Rosebell, plus Henry (33) Charlie (30) and Claude (20). Henry and Charlie are both recorded as married, but no wives are in evidence: only Claude is single.