My version of “/etc/apt/sources.list” is just the original with the commented-out entries uncommented (then run “sudo apt update” to make those changes visible). This would be the easiest way to get the package (this would be the most recent mc from Ubuntu).
In Case You Want to Compile Your Own Anyway…
If you go to do the actual install you’ll see a number of dependencies listed…these are basically libraries for use without C headers or other development content (the already-built program uses this)…you’d need the dev package in addition to the base package (the compiler needs the supporting package header files). To find dev package versions your apt directory may need additional edits. Note that in sources.list that “deb” at the start is for main packages, “deb-src” can be added with the same URL to make apt searches also show source packages. Dev packages and source packages then show up…because dev have headers for compiling against these are what you’d want. Source packages are for building and modifying your own version of a library or package, and not needed for your purposes.
So uncommenting what is shown in the default sources.list implies you will see “mc” and its related “mc-data” package. mc files other than those are for development or debugging. I’m not sure which repo would have the mc source, but dev does make debug symbols available, as well as dev packages needed for when you do have mc source and want to compile (the supporting library infrastructure’s headers).