I'm not against learning C in general. I think everyone should. But his question isn't should he learn C ever it's should he learn it in his spare time between High School and College
The best thing I did for myself during college was to program on my own time in languages that people use out in the world. Learning C, Assembly, Data Structures and all the rest is great but when you get out into the world it helps to have been programming in Python or Ruby for 4 years and be experienced in that.
So I say "No". Learn C in school but in your free time I suggest you learn Python (Here's a great starter book I used when I taught a class on it: http://www.amazon.com/Python-Programming-Absolute-Beginner-3...)