No Ramya mostly no because MAT conducted in May 2018 is for getting admission in all the b-schools for next session of 2019-21 only. Most of the colleges' application deadline closes in March and second round process is also completed or going on so it's not possible to use MAT may score for this session only but you can use this score for next session.

One good thing about giving MAT exam in May 2018 is that you can get to know your score and position where you stand. Through last year cut-off records you can also estimate the colleges in which you have a good probability of getting a call. And if your scores are not good enough to get a call from your dream b-schools then you can re-appear for MAT exam happening consecutively in Oct, Dec, Feb.

All the best for your preparations!!