Hello Devendra

The thing is, Maths and Computing is much different in all IITs. The course structure is different. So we can't generalise whether “Mathematics and Computing” as a general term, is better or not.

Suppose if you want to get into pure Maths as a career, the closest you can get to it except for MnC in IITs, is CSE. Here, MnC is obviously a better option. MnC at IIT K would be the best in this case.

Suppose you want to get into Algorithms or Databases or OS or software development or any other standard CS stuff. CSE is your best bet in an IIT, if you don't get it, then go for MnC as it is the closest option.

Suppose you want to get into Computational stuff such as Data Science, Statistics, Machine Learning, Artificial Intelligence etc which require more Maths rigour as compared to the exposure to OS/softwares etc. In this case, a BTech (not BSc) in MnC will be more helpful than the standard CSE. Your best options will be IIT Guwahati/KGP/Hyd/BHU etc.

Go through the syllabus you're going to be taught. See if it offers exactly what you want. That's how you go for a branch. Nothing can be called “better” than the other. Also, the final outcome, the place you reach after your Bachelors years, depends more on how you used your resources, than how good the resources were.