Hello Alison,
Welcome to planDisney! You're going to have an amazing time at
Disney After Hours! I've always wanted to try this event. How can you help but have a magical evening when it includes free Mickey Ice Cream bars?! Woo hoo!
On the evening of your Disney After Hours, you'll be able to enter Magic Kingdom starting at 7:00 pm. I checked with a Cast Member, and they couldn't guarantee that the monorail will still be running at 1:00 am, after your event concludes. The Disney World website does state that
Monorail Transportation is available for one hour after Magic Kingdom closes. And the friendly Cast Member assured me that there will absolutely be some form of Disney transportation available at 1:00 am to get you back to your Disney resort after this fun event. I'd maybe ask the Cast Members at your resort that day, before heading out to the party? They may know better what to expect for your transportation options that evening.
Enjoy riding all the rides, and taking advantage of those short wait times, Alison! I hope this helps. Please visit us again at planDisney if you think of any additional questions.
See ya' real soon!
Tami