As an 11b in the Massachusetts Army National Guard, I want to be a Ranger. Can I being NG and not active?

You can go to Ranger school and be Ranger Qualified, and some would call that being a Ranger. But you cannot be in the NG and be a member of the 75th Ranger Regiment at the same time.
So, you can earn your tab, and be called a Ranger. Or, you can go to RASP and earn your Beret and Scroll and be a Ranger in the 75th.

You can go to Ranger School and earn your SQI to either make you a "Ranger Qualified" (G) or (V) "Ranger Parachutist," but that will not make you a Ranger in the special operations sense. The only way to do that is to attempt to join the 75th Ranger Regiment and complete RASP. Many of our infantry positions are SQI G coded in the National Guard if that is your intent. The National Guard also has 19th and 20th Group Special Forces if you would rather go that route.

You can go to Ranger school and earn a tab if that is your question.