For the commonwealth of MA tax return we are being asked if we are covered by an MCC. What is an MCC? we are both on Medicare. Is Medicare considered an MCC?

MCC = Minimum Creditable Coverage. If you had private insurance coverage, you'd have to have a Form 1099-HC sent to you proving that your carrier meets those rules. 

However, you are on Medicare, so the answer to the question is Yes. When you get to the question "What type of health insurance did you have in 2016?" make sure you click "You had something else" and click "Medicare".