Without shelling out:

#!/usr/bin/env perl 
use strict;
use warnings;
use Path::Tiny;

chomp (my @SetBCs = <DATA>);
for my $fname (@SetBCs) {
    next unless $fname;
    my @command = grep {/Sets/ .. /Rules/} path ($fname)->lines;
    print @command;
}

__DATA__
C:/ProcessFiles/File1.txt


C:/ProcessFiles/File2.txt
C:/ProcessFiles/File3.txt
C:/ProcessFiles/File4.txt
C:/ProcessFiles/File5.txt
[download]

That's just one way. You can put your loading of @SetBCs back to reading from the file, but the rest of it should work fine as-is.