"How are" or "How is" the wife and kid?
- How are the wife and kid?
- How is the wife and kid?
Which is more correct?
"Are" is correct for most compound subjects, except for singular meanings (i.e. mac and cheese is) and alternative subjects (you or your wife is -- you or your friends are, though -- matches subject closest to the verb). Yay for style manuals.
It's not a question of "more" correct. The first (using "are") is correct, and the second (using "is") is not.