I started this quest:
http://www.uesp.net/wiki/Oblivion:Mazoga_the_Orc_(quest)
Unfortunately, when I went to talk to Mazoga, I found that two Imperial Guardsmen were attacking her. She was quickly slain and I cannot continue the quest(s). Her body still lies there, so is there a way to fix this?
Thanks in advance for any help.

Your simplest bet (regardless of platform you are playing on) would be to reload a save from before you entered the Great Hall. Then make a good save just before entering the hall and try it. If the situation is the same, avoid the castle for at least three in-game days to allow everyone inside time for their AI to reset and try again. Good luck. I have not seen this problem during my games, but it is not unheard of; after all, Mazoga is a bit cranky until you get to know her.