If Asalam dies you'll be unable to use the inn at Gran Soren between eight and ten days (perhaps randomly chosen by the game?) until Asalam resurrects and stands behind the counter again.
Escort quests are a good opportunity to use the "Save and Continue" feature. After you defeat any monsters you encounter and your escortee is still alive, then "Save and Continue" and move on. If your escortee dies, then load from your last save and try again.
Also bring along some group healing remedies, as your escortee reaps the benefits of group healing plants and potions.