If the account is supposed to be the killer's account, change thePlayer to killer...
function killReward (totalAmmo, killer, killerweapon, bodypart, stealth)
local accountname = getAccountName(getPlayerAccount(killer))
if isObjectInACLGroup("user." .. accountname, aclGetGroup("VIP")) then
if (killer) and (killer ~= source) then
givePlayerMoney (killer, 1000)
end
end
end
addEventHandler ("onZombieWasted", getRootElement(), killReward)