Sure, fine, Infernal Healing on the girl.
Magical healing doesn't care if your skull is the wrong shape and your brain squished inside; it's not paying attention to information theory. She doesn't use it on commoners much, because the Worldwound doesn't have an abundance of commoners. (There are periodic proposals to import some, but they'd eat food, and that makes them expensive). She could tell you that in principle it ought to over the course of one minute heal a commoner anywhere better than 'on the brink of death' to perfect health, and at least get a commoner who is on the brink of death to stop dying on you.
She doesn't stick around for a minute to watch the girl wake up, because a bunch of the rest of these people are dying too.
If they had a Good cleric everyone would be right as rain a couple seconds from now but Carissa does not, quite, dare propose they try praying to the Good gods. Instead she'll try battlefield first aid. The Chelish form of battlefield first aid for wizards is heating up the tip of your dagger with Prestidigitation and cauterizing bleeding bits of people.
She's not actually entirely sure this is a helpful thing to do if you have no magic healing for them later either, but even if it just means they die more slowly it'll mean they can do the heads one at a time instead of all at once.
Are the people with the not-Final-Blade out of the Rope Trick yet?