It would be tough to tell you the exact as the cutoff varies every year & NIT admission depends on the various factors like Category, Home state Quota/ Other state quota, Branches etc. But try to score more than 200-220 around as a gneral category to get the top branches in MNNIT Allahabad. You can also check the previous year cutoff rank with the given below link.

MNNIT Allahabad Cutoff

Good Luck!