Teen boy's going away to college. immature in taking care of his business matters. should mom do it?

No: How will he ever learn to handle his own responsibilities of daily living until you let go and let him experience, for better or worse, the consequences of his actions (or inactions).

Beware : This is a good opportunity to teach life skills and responsibility! however, too much freedom and control could be dangerous. Give responsibility in small amounts and look for teachable moments!