from __future__ import print_function # если python2
import os
import re

words = ('msh', 'mat', 'dds')

r1 = re.compile(b'[\x20-\x7F]+')
r2 = re.compile('|'.join(map(re.escape, words)))

for fname in os.listdir('InputFiles'):
    with open(os.path.join('InputFiles', fname), 'rb') as i:
        with open(os.path.join('OutputFiles', fname), 'w') as o:
            for txt in filter(r2.search, map(bytes.decode, r1.findall(i.read()))):
                print(txt, file=o)