Thanks for the info. Though the issue at hand is a little bit different here .
Thing is that i already have the Thjorad . I took it way before i even completed the Lich quest. I had it in the inventory all this time. So the problem is not with the bells etc, all that has been done when i got Thjorad in the first place, and everything was fine, everybody behaved as if nothing happened.
The thing is that now when i got their lost relic from the Wizard's Lab in Yorwick, and want to give it back to them, I cannot because the moment I step into the Monastery they attack all of a sudden. So i am wondering if there is any way i can make them all calm again, obviously without having to whack them all ;].