is there any other better regex which will work instead of the given one?

Of course, "There Is More Than One Way To Do It"!

It all depends how you define your matches. It seems you want to reject all lines with a sequence of

1. two (or more) single quotes
2. two (or more) full stops
3. single quote, full stop
4. full stop, single quote
5. ...

In other words any sequence of full stops and single quotes without other characters in between.

You can therefore search for this rejection pattern and accept all lines which are not matched by the rejection pattern.

use strict;
use warnings;

while (<DATA>) {
    if (/['.]{2,}/) {
        print "Rejected: $_";
    }
    else {
        print "Accepted: $_";
    }
} 

__DATA__
St.John's high school.
A. B. C. school.
Institute of management.
oxford university.
A.B.C college.
Ragu ram's college of technology.
A..B.C college.
St.John''s high school.
St.John'.'s high school.
[download]

Is this regex better? That --again-- depends. If your "match" pattern is rather complicated or the strings to match are long, it can take a while to run and sometimes the "rejection" pattern is simpler as it will stop as soon as one of the rejection cases is found.

In case of doubt, just profile your code and see what performs best.