I am not aware about condition of Allahabad.
But i think you should taken bus to Kanpur, Faizabad, Raibareilly etc. so that you can change bus en-route.
Many times i took Bus from Firozabad and Agra in late night(No metter 9-10, 2-3, 4-5) and never faced such problem.
It also possible that due to festival, all buses were departed early.