Question: are mcgonagall and filch related?
Answer: Professor Minerva McGonagall is no way Argus Filch's mother. For a reason i can tell you that professor was born in 1935 and argus filch was born somewhere near the 1930's too. So that anyway means that professor is by no means argus Filch's mother. No professor McGonagall is not Filch's mom.