At some point given her reaction to Harry when he said he was leaving her behind, I see Murphy leaving Mac's place to do battle or try to. If Mac is what we think he is, he may have the power to heal her. The question then becomes, will he? On one hand if he is a watcher it would be against the rules, free will and all of that. However if he is one of the lustful ones and fell, maybe not so much. We know as early as Storm Front he has aided Harry, i.e. giving him the keys to his Trans Am, so he might help Murphy. Then again when he added his blood to the Placard, he was making another statement and feel that he cannot heal her as much as he'd like to.
But if Murphy gets killed this will be how, I can see Harry returning to Mac's place after the battle only to find out Murphy isn't there, then finding her body in the blood and rubble.