The following code shows one way to tackle this problem:

#! perl
use Modern::Perl;

my $file1  = 'amayaM   vismayaM   souraM  kamalZ';
my $file2  = 'amayamAn vismayamAn souramA kamalAni';
my %words1 =  map { $_ => undef } split /\s+/, $file1;
my @words2 =  split /\s+/, $file2;

for my $word2 (@words2)
{
    for my $word1 (keys %words1)
    {
        my $stem = substr($word1, 0, -1);
        my $len  = length $stem;

        if (substr($word2, 0, $len) eq $stem)
        {
            say $word1, ' -> ', $word2, ' -> ', $stem, '+', substr($wo
+rd2, $len);
            last;
        }
    }
}
[download]

Output:

19:21 >perl 415_SoPW.pl
amayaM -> amayamAn -> amaya+mAn
vismayaM -> vismayamAn -> vismaya+mAn
souraM -> souramA -> soura+mA
kamalZ -> kamalAni -> kamal+Ani

19:22 >
[download]

Hope that helps,