I agree with Francisco that the fact that your friend is appearing in your dreams each night is a clear sign that something is up. I would assume that either something has happened or perhaps she is also thinking of you.
Reaching out to her family is a good option- how about the mutual friend you were living with in the apartment? If you are still in touch, perhaps they might have a clue on Kelly’s whereabouts.
If you are struggling to find clues, I’d suggest consulting with divination tools. Perhaps you could try a reading with either a pendulum [quick and easy guide on How to Use a Pendulum] or tarot cards [here’s a guide on How to Read Tarot]. Even a simple reading inquiring if Kelly is okay and staying healthy may help to put your worries to rest and decrease the frequency of the dreams.
Wishing you the best of luck reconnecting with your old friend! Blessed be 