America runs on Dunkin, except on certain holidays. Easter is one of those holidays where a Dunkin' Donuts location near you may choose on its own to be open or closed - it's entirely up to the franchise. Your best bet is to call your local Dunkin' Donuts franchise ahead of time to inquire about whether or not they are open.
Here is a Dunkin' Donuts locations link with phone numbers provided.
Dunkin' Donuts if offering many seasonal food options along with seasonal-themed beverages, including Girl Scout Cookie inspired flavors like Thin Mint, Coconut Caramel and Peanut Butter Cookie.
As for liquor stores, this depends on the state in which you live. Massachusetts liquor stores will be open (they are only required to be closed on Thanksgiving and Christmas Day). However, some liquor stores across the state may be closed on their own accord.
In Pennsylvania, all liquor stores are required to be closed on Easter Sunday.
Here is more information on what is open and closed on Easter Sunday, as well as the Monday following the holiday.