Conjugate base of H2SO4 is:

Conjugate base: the ion formed by the release of one proton from acid is the conjugate base.

The conjugate base of H₂SO₂ is HSO^-₄ (bisulphate ion).

H₂SO₂ ⇋ HSO^-₄ + H⁺

Hence the correct answer is B i.e. bisulphate ion.