Can I freeze muffin mixture?
Muffins are a quick bread, same as waffles, so the answer to Can you freeze waffle batter? applies equally well here.

You can freeze it, and it will keep the batter from spoiling, but it will not maintain the quality.  It won't rise very well when you thaw it and try to bake it.

I would suggest that instead, you freeze the wet and dry ingredients separately; measure them out into the portion sizes that you intend to use, and when you want to make more muffins, combine them after thawing them.

(Or, as Joe suggests - just freeze the finished muffins themselves.)