Substitute for milk in muffin recipe

If it's a food allergy, then Picnic's suggestion isn't possible.
It depends on the type of muffin. I've used both applesauce and home-boiled pumpkin (more watery than canned). Might add a spoon of oil, and less sweetner if needed. Corn based muffins, try a broth (not too salty)
Shredded zucchini (don't release juices inside) plus water also works.

I use almond mild, flavour is better than milk

I use sour cream or creme fraiche in lieu of milk in baked goods.