Dear aspirant, 

       since, you have only 1 backlog and also as you have chances of leaving or ommiting any 2 subjects, so you can leave the subject and proceed further. and, you will not be allowed for admission into M.tech if you have any standing arrears in undergraduation. So, i personally suggest you to leave that subject since you have chances to omit the subjects. And do remember that you cannot write  the competetive exams such as GATE, CAT, etc.., 

feel free to ask us to help you further regarding anyother queries and concers and you can ask in the comment section below !!

hope this helps you !! 

 good luck !!