If your classmate is in Changsha now, it is easy to apply for a health certificate, and even a big hospital can do it. You just need to ask at the service desk of the hospital. Now the hospital is very standardized in handling these certificates.
However, it should be hard to find a job with food and shelter. Unless you are a waiter, you may be able to have food and shelter. Some big companies will have canteens, so it is good to provide a free meal. Good luck to your classmates!