eCPPT isn't as difficult as OSCP, so that might help bridge the gap between CEH and OSCP a bit (which is enormous).
Python will probably be more useful day-to-day. C will help you better understand exploit development, how memory's used, etc., but unless you're writing something that needs to be extremely efficient (i.e. a password cracker), using C is going to be a pain for most tasks.
The day you stop learning is the day you start becoming obsolete.