Back in the mists of time, there was a thing called CGI-IRC written in perl that you deployed as an nph CGI script and would then do real time comms; I think (vague memory) the original authors an ircatwork.com using it and then eventually started mibbit.

I don't recall seeing one written in C, I think the last time I saw a CGI script written in C was a some years ago version of Nagios