In my opinion, your classmate's subconscious should be afraid of diseases or health problems, so in his dream, the hospital is a symbol of terror, and you are the one who can give him a sense of security. He should trust you more.
It seems that my guess is reasonable, hehe.
I think she is in poor health and young, so it is easy to worry about health and life. After all, youth gives people the overall concept of health and vitality, so she may be very sensitive to hospitals or some information related to death (such as ghosts and zombies), thus becoming a symbol of what she fears most. Of course, this is just her subconscious. When she is rational (such as during the day), her rational psychological mechanism will consciously suppress these thoughts. So she can't show it, but during her sleep (when people's consciousness is relatively relaxed), her subconscious mind-this fear of death and disease-will be expressed in the form of escaping from gloomy hospitals or ghosts and other dreams.
As for her always dreaming of you to save her, it certainly means that your impression in her mind is safe and reliable. Why are you reliable to her? Maybe she often talks to you about this, and you give her a lot of comfort; It is also possible that she just got a sense of warmth and security from your appearance, personality and so on. As for whether or not to fall in love, it's hard to say, but everyone has a good impression. Maybe it's love, maybe it's just simple dependence.
Do you distrust you when you say that she no longer has such dreams? I don't think so. It can only show that she is not as afraid of these things as before, and her worries about a healthy life are much lower.
Ha ha, personal advice, for reference only!