I currently have a tenant at will agreement with my landlord where we are supposed to give 30 days notice before moving out. However, my husband accepted a job in Florida(currently in ma) and we only have 2 weeks before we have to leave. 3o days notice is not possible. We have already paid for the month of May and are leaving before the month is even over (May 25)... Can we ask for the last months rent back if we are not going to use it?

You can ask for it, he most likely will laugh at you, he can ans will most likely hold you liable for 30 days from when you gave noticce,

So from the day you gave notice, you may owe him a few days rent into next month.