-Does she have advance parole in hand? If no, she needs to go to the local USCIS Office to get the emergency advance parole to the travel. Bring a completed Form I-131, passport, I-485 receipt and the evidence of the emergency, i.e. the illness proof (Dr. letter/diagnosis, or hospital letter)-translate it into English by your friend himself, not need to notarize it. The proof can be scanned in China and email to your friend.
非常感謝