Do you have someone you can practice interviewing with? This is just an idea, but maybe you and a friend can slowly warm up to a challenging interview by working on one bit at a time, taking it slow. And I mean slow. Like maybe this weekend you can do an “interview” for a maximum of 5 minutes, and only practice introducing yourself. Then do it again next weekend. If you get comfortable, make it 6 minutes the third week and start talking about your past work. Then 7 minutes and include what you’re seeking out of your future job. Then 8 minutes and have them start to ask challenging questions. Also, this might be horrible advice because I don’t know you and I also hate interviewing! I will say, when you interview, be your authentic self because if they hire you as your inauthentic self, it might not end up being a great fit.
That is really stressful and sad. Try to be there for her but also keep in mind what is and is not inside your (and her) sphere of influence. But you can’t give yourself away for her. I hope she pulls through soon.