You will need

Sweater
3-6mths - 1 Ball
6-9mths - 2 Balls
9-12mths - 2 Balls
12-18mths - 3 Balls

Cardigan
3-6mths - 1 Ball
6-9mths - 2 Balls
9-12mths - 2 Balls
12-18mths - 3 Balls

Hat and Scarf
3-6mths - 2 Balls
6-9mths - 2 Balls
9-12mths - 2 Balls
12-18mths - 2 Balls   

3.25mm, 3.75mm and 4mm Needles
Cable Needle
4 (5 : 5 : 5) Buttons for Cardigan
1 Button for Sweater
3 metres of narrow ribbon for Girls Hat and Scarf