I think Omid and Christa are some of the finest human beings we have met in the game thus far. We can count on them. They care for Clem and will not abandon her.
That being said, the city is overrun with walkers. I doubt the train depot is walker free. Anyone who is alive is running towards the countryside. That's where Clem, Omid and Christa stopped running long enough to pause and notice one another.