First phone round friends begging for temporary freezer space, then open the door/lid and check the situation. Try to find out how long the power has been off (cross-question all suspects!)
If the nearer things are still frozen hard, the stuff further from the door is probably still frozen too, so pile things into bags and boxes and get them to friends' freezers as fast as possible, then return and defrost freezer ready to put everything back.
If things are starting to soften, do triage. Three piles - one of things like bread, which can be refrozen, one of things that are obviously beyond hope and have be thrown out, like melted icecream, and one of things that will be fine if you cook them and then refreeze. Then be prepared for a massive cooking marathon.
Are her freezer contents insured? Mine were, when this happened to me, but they need a detailed list of what had been in it, and could ask for "evidence" if she claims that it was full of fillet steak, lobster and caviar, (though they didn't demand evidence for my sausages and garden peas etc) So keep a note of every frozen sprout.