There is actually no Monorail between the Magic Kingdom and Epcot. You would need to take the Express Monorail from the Magic Kingdom to the Transportation & Ticket Center, then from there you would take the Epcot Monorail. So the question is what time would Epcot be closing on the night you are coming from the TTC, because the Monorail between the TTC and Epcot would usually run for an hour or maybe more after Epcot closes.