Answer is 2.25 mol.
Explanation;
The balanced reaction equation is
2KMnO₄ + 5H₂O₂ + 3H₂SO₄ → K₂SO₄ + 2MnSO₄ + 8H₂O + 5O₂
The stoichiometric ratio between KMnO₄ and H₂O₂ is 2 : 5.
Hence,
moles of reacted H₂O₂ = moles of KMnO₄ reacted x (5/2)
= 0.90 mol x (5/2)
= 2.25 mol
Hence, your answer is correct.