How should I prepare for the MMMUT B Tech 2021 in 1 month?

It does not matter how much time you have before the exam. It is about planning your preparation, covering the topics, and revising them. You need to utilize the one month in your hand very efficiently. 

As you are about to give the MET, it implies that you have just cleared your board exams. You do not need to do anything extra but just be thorough with whatever you have studied. 

You just need to practice well for the numerical and keep your basics clear. Do not waste much time on anything new. 

The cut-offs vary greatly every year according to the merit list so do not rely much on the previous years’ cut-offs. Just make every topic in your mind clear theoretically and put in some smart work such as managing time and building some strategies and you will do very well in the exam.