I am pleased to release into the public domain an example MUD client written in C (source only). It was developed in Unix, but should compile OK under Cygwin (on Windows) with minor changes to 'include' files.
This program is only a simple example (296 lines of code), however if you are interested in seeing how a client works, or wanting to write your own, you could use this as a basis for it.
The code is not copyright, so you can use it as you will.
Download it from http://www.gammon.com.au/files/muds/tinyclient-1.0.0.tar.gz (4 Kb).