I have found two molds of M & C Ponies.
This one is 3.5″ tall and marked M & C on one back hoof. It is similar to Lanard Party Ponies.
This is a fakie version of the above with no hoof markings:
This one is also 3.5″ tall and marked M & C CHINA / 2175-37 on back hooves. The head is a different shape than the above mold. May or may not have a unicorn horn.
This 3″ baby is marked CHINA on one back hoof. I’m not 100% sure that she is part of the same collection.