How can i get one of my friends forgive the other one? this is making them both really sick !! :(?

well, i have this friend let's call her S and another one let's call he M .. me and M were trying to reach S for the last 8 days but we couldnt reach her cause everytime we call her cel there is no answer .. we were on vication and yesterday that vication ended and we went to the uni but she didnt show up so we were worried .. and today in the morning me and M receved a mage which means that S died (it was sent from her no ) .. i was really shocked and i was seriously shaking and so frastraited about the sad news .. and i thought about M b coz she is so sensitive .. she called right way crying and yelling .. and she hung up after i told her that i will right with u (she was in the uni) .. b4 i arrive another friend called me telling me that that was a JOKE !! and that S is alive .. i was really mad .. i've arrived to the uni looking 4 them .. i've found them both crying and M was really tired and she was laying on the floor and S was saying SORRY to her .. but M cant forgive S