It is most likely a C1. You can identify it by the following specs: 12 frets; single markers on the 5th and 10th frets, double markers on the 7th fret; the exterior binding is faux tortoise shell.
There were a few style 2 concert ukuleles made, but they are exceedingly rare. Were it a style 2, the outer binding on the body would be white, or ivoroid as it is called. Don't be confused, the Style 1 of this period with clearly show a thin white line of purling, but the outer material, the binding, is the darker, tortoise. The outermost layer on the style 2 is white.
If it is in great condition, it could fetch about $1,500, particularly if it comes with the original case (also in great shape), although they most often bring considerably less...about half that much if they are noticeably played.