score:3
Since you haven't told us where you are, I'll assume you're somewhere else within or near by Mexico City. Your best bet will be a taxi.
Public transport (buses and trains) don't start until 4:30am or later:
Metro (trains)
Monday thru Friday from 5:00 to 24:00 hrs.
Saturdays 6:00 to 24:00 hrs.
Sundays and Holidays 7:00 to 24:00 hrs.Metrobus
Monday thru Friday from 4:30 to 24:00 hrs.
Saturdays and Sundays 5:00 to 24:00 hrs.
source; in Spanish