While technically not a Halloween episode, this Brady Bunch story involves the kids trying to keep their parents from selling the house by scaring away the potential buyer. "To Move or Not To Move" will satisfy your cravings to see children posing as ghosts under bedsheets, to hear strange creaking noises throughout the house, and to see Alice holding up an amulet to protect herself from evil spirits. From the show's first season, the episode originally aired 6 March 1970, which is why the character Mrs. Hunsaker quips, "I must say, you people celebrate Halloween at a strange time of year."
Watch this episode on CBS.com
Other Brady Bunch episodes that could be categorized as Halloween-related are "The Slumber Caper" (1970), "Fright Night" (1972), "Two Petes in a Pod" (1974), and "Out of This World" (1974), which is similar to "Fright Night" but involves a UFO instead of a ghost.