Although a great deal of ink has been spilled on the supposed origin of Hallowe'en traditions, actual records suggest that almost all of the Hallowe'en traditions we know, from trick-or-treating to dressing up as monsters to ghoulish decorations arose within the past 100-150 years.
The only Hallowe'en tradition that has any claim to a reasonable antiquity of at least a few centuries is the lighting of bonfires–though it's rarely practiced nowadays.