I have only once been to Allahabad jn, back in 2012. That was month of october diwali time. We three friends, two going to lucknow and me to bareilly boarded pune-patna express from pune. We planned for going till allahabad in this train and then will see to it for reaching lucknow. Both my friends were bit of over-confident regarding allahabad. They said, "bhai UP pahunch jaye, fir waha se kaise bhi lucknow chale jayenge." I was like ok, do whatever. Bas mujhe lucknow pahuncha do.
Somehow the confirmed seat of sleeper didn't helped us lot in terms of safety and luxury as around 150-180 people were travelling in our coach (diwali rush). Fog was not much, so we reached ALD...
more...

by 2130hr. We checked out and found that even the ALD-HW triweekly was not running that day. So from here we went to the bus stand. There biggest shock we got that no upsrtc bus is left for lucknow. Last bus left at 2100hrs. Next bus is at morning 0500hrs. We returned back to railway station and waited outside for some snacks and refreshment. There we talked with a driver (indigo car) and he told us he is going to lucknow. He can give us lift but will take Rs. 200 per person. We didn't had much of choice and boarded it. But that kamina driver added 3 more people for lucknow. He said "saheb badi gaadi hai, 3 logo mein loss ho jayega."
Somehow we six+driver adjusted in that indigo. By night the fog also got severed. And the highway was nearly empty. After travelling around 80-100km, the driver halted at a petrol station and asked all of us to give some money extra (Rs 50 per person) for filling the tank. We objected for this and told him that he didn't said this extra money before boarding. He replied "saheb ye sabko pata hota hai. Ab car hai. Petrol toh bharna hi padega." He directly said petrol bharao, otherwise gaadi aage nahi jayegi. And then we got to know that this petrol station was his friends pump. The people at pump also came near us and started arguing with us for giving money. After very heated argument we all decided to give 200 more. The driver filled up his tank and then drove. He left all of us at about 0330hrs near lucknow kaiserbagh stand and went away. From here i waited and took upsrtc bus to bareilly.
Now here my motive was only this-If by chance you are reaching allahabad or lucknow or varanasi or mughalsarai like cities in UP at late night time and have to go to some other city, then either opt for train (best and safest) or else get prior knowledge regarding the last upsrtc buses from that city. If you come up these kind of situation then don't look for private drivers and cab owners (there would be many). Wait till the dawn and take the first morning bus. UPSRTC buses are pretty safe.