Sally misses the Trick or Treat because she is with Linus in the pumpkin patch. After you bring her a bag of candy, she leaves. Violet is one of the trick-or-treaters, along with Lucy, Pigpen, and Charlie Brown. Neither is present at the very end of the quest.
You give it to Sally in the pumpkin patch. She missed trick-or-treating.
Take the bag of treats to Linus and Sally in the pumpkin patch. This is essentially the end of the quest, as Sally will leave and Lucy will bring you the Island Medallion.
It never does. You complete the island by bringing your trick-or-treat candy to Sally in the pumpkin patch. (see the related question)
After you have collected the Trick or treat candy, take it to the pumpkin patch and give it to Sally. After Snoopy appears and Sally leaves, you will fade to later that night and Lucy will give you the Island Medallion.
You go to the pumpkin patch and give it to Sally. She leaves and then Lucy will come get Linus and award you with the Island Medallion.
Once you finish trick-or-treating, take the candy to the pumpkin patch and give it to Sally.
After you have collected the Trick or treat candy, take it to the pumpkin patch and give it to Sally. After Snoopy appears, and Sally leaves, you will fade to later that night and Lucy will give you the Island Medallion. (see related solution question below)
After you complete all 4 games at the Halloween party, you go trick-or-treating with the gang. Bring a bag of candy to Sally in the pumpkin patch.
Linus and Sally
After trick-or-treating, you give the candy to Sally in the pumpkin patch.You give the lemon flavored sucker to Linus.You give the candy BAG to Pigpen.
After you have collected the Trick or treat candy, take it to the pumpkin patch and give it to Sally. After Snoopy appears, and Sally leaves, you will fade to later that night and Lucy will give you the Island Medallion. (see related solution question below)
Nothing. This is the end of the quest. After Snoopy shows up and Sally leaves, the scene fades to later, when Lucy comes to get Linus and gives you the Medallion.