yeah, 5 string model is either B,E,A,D,G (low B) or E,A,D,G,C (high C) or E,A,D,G,B (not so common). drop c would be covered by B,E,A,D,G. the low B will have the C in first fret position.
If your guitarists play in drop C, they're probably tuned CGCFAD and are asking you to tune to GCGCF. You will get mud—just play in BEADG and know your notes... or play with .50s