undergrad cs and business school

Won't matter. What matters most is that you have a good enough gmat score and your essays which should demonstrate quality work/life experiences. If your work experiences don't indicate high levels of responsibility, a lot of people aim for quality responsibility in their community i.e. Red Cross chapter etc.

One grade won't ding you. You're in a good place.

I think that a C in something like introductory Econ or Accounting could hurt but that a C in some irrelevant class would not do much damage to an application

B-school isn't law or med school. I hate using the phrase, but it is definitely more "big picture" --- with the exception of having a shit gmat score.

It's an overall picture. Assuming your overall grades are fine, you'll be good to go. There are so many more variables in the picture and so many years between now and then. To give personal experience, I got in to plenty of schools with a 3.2 and a C in calculus, which is a class that Sloan specifically calls out in their application. Still managed.