I never tried the MEM mod, and I don't know much about it -- including when it was first made.
But if you're using a (recent? GOG?) single-player version, and a normal epic-game doesn't give you these text-errors, that would strongly suggest to me that the MEM-specific labels.txt was actually adapted from the original multiplayer version of C3C (running on GameSpy, at that time).
If so, then you will need to go into your ..Conquests/Scenarios/[MEM]*/Text/ folder, and use any basic text-editor to open the labels.txt file that you should be able to find there. Then scroll down until you find the 2 lines "Ping"and "Host". If there is another line "Unknown" in between them, delete it, so that the file now looks like this
...
Ping
Host
...
Save and close the file, and start a test-game of MEM (you could also continue from a previous save, if you have one). If the problem is now fixed, then great, you can carry on. If not, let us know and maybe someone will be able to suggest something else.
* "[MEM]" here is just a placeholder, because I don't actually know what the MEM mod-maker called their mod-folder. But presumably you do...