Mousse does not qualify for a free food allowance so it will be a straight 1 syn per 20 calories. Looks like 4 syns on a quick scan.
The Muller Vitality are not fat free or sugar free so have syns in too:
Muller, Vitality Prebiotic Fibre & Probiotic Low Fat Yogurt, Cherry, 125g pot 2½
Muller, Vitality Prebiotic Fibre & Probiotic Low Fat Yogurt Drink, Raspberry, 100g bottle 3½
Muller, Vitality Prebiotic Fibre & Probiotic Low Fat Yogurt Drink, Peach, 100g bottle 3½
Muller, Vitality Prebiotic Fibre & Probiotic Low Fat Yogurt, Strawberry, 125g pot 2½
Muller, Vitality Prebiotic Fibre & Probiotic Low Fat Yogurt, Raspberry, 125g pot 2½
Muller, Vitality Prebiotic Fibre & Probiotic Low Fat Yogurt Drink, Vanilla, 100g bottle 3½
Muller, Vitality Prebiotic Fibre & Probiotic Low Fat Yogurt, Peach & Passionfruit, 125g pot 2½
Muller, Vitality Prebiotic Fibre & Probiotic Low Fat Yogurt Drink, Strawberry, 100g bottle 3½