i just did that quest myself yesterday no issues.
The guards come out of boxes that are at the corners of the castle on the ground. Fromt the cave to the entrance of the town you will run by two corners of the castle, at each corner, there should be two boxes each. All i did was once i found two boxes killed the guards, waited for a moment, backed up, walked by again and they respawned to kill last two.
if you dont see boxes there then id file a bug report maybe its only your servor issue? idk.
Misguidedknight 72S/72K/70R Retired
Cerburus 100Wd/100S/100W/100R/100D/70M
Misguided 100CH/100R/100M/68WL/88P/52W
Sober 100K/60P/60W <-best toon name for anyone that knows me
Once proud co-leader of Exiled Demon Horde.
Been on multiple servors
Started playing around lvl 55 Cap...
Easycompany