You should ideally choose a career path which you think
you can excel, knowing your strengths. Those job listings
are not writings on the wall. By the time you graduate, they
would anyway change in their color and content.
And there won't be any ' bioinformatics+ c' programming
books. You first need to understand what bio informatics
and then programmming is just another tool to solve problems
you encounter. Whatever you could do that in C, you can
achieve in Java,Python, Ruby, FORTRAN- anything.
You got to be good at basics of mathematics very well.
It has lots of statistical tools, nothing to sneeze at.
So you are now educated on what to look for. All the
best!