Clue 1: The child dressed as the monster has collected 20 sweets.
Clue 1: The child dressed as the monster has collected 20 sweets.
Clue 2: Danny is not wearing a witch costume.
Clue 3: Jodie has collected the fewest sweets of all four children.
Clue 4: The child dressed as the spooky ghost has collected five more sweets than the monster.
Clue 5: Seb's goody bag contains 20 sweets.
Clue 6: Natasha is the child wearing the orange pumpkin costume.
Clue 7: The monster costume is not worn by Jodie or Danny.
Clue 8: Natasha has collected five more sweets than the child dressed as the ghost, and Natasha is not the witch.

1. Seb has 20 sweets (Clue 5), and the child dressed as the monster also has 20 sweets (Clue 1). So, Seb is the one dressed as the monster.

2. Jodie has collected the fewest sweets, so she has 15 sweets (Clue 3).

3. Natasha is wearing the pumpkin costume (Clue 6) and has five more sweets than the child dressed as the ghost (Clue 8). Therefore, the child dressed as the ghost has 25 sweets, meaning Natasha must have 30 sweets. Since Seb is not the ghost, Danny must be the one dressed as the ghost.

4. Danny is not wearing the witch costume (Clue 2) and he is the ghost with 25 sweets (Clue 4).

5. Since Jodie cannot be the monster or the ghost, she must be dressed as the witch, and she has 15 sweets.

   Final Answer:
6. Jodie: 15 sweets, Witch costume.
7. Danny: 25 sweets, Ghost costume.
8. Seb: 20 sweets, Monster costume.
9. Natasha: 30 sweets, Pumpkin costume.