the balanced equation for the neutralisation reaction is as follows
2LiOH + H₂SO₄ ---> Li₂SO₄ + 2H₂O
stoichiometry of LiOH to H₂SO₄ is 2:1
both LiOH and H₂SO₄ are strong bases and strong acids respectively, therefore they completely ionise into their respective ions
1 mol of H₂SO₄ is neutralised by 2 mol of H₂SO₄
therefore 2.0 mol of H₂SO₄ is neutralised by - 2 x 2.0 = 4.0 mol of LiOH
4.0 mol of LiOH is required to neutralise 2.0 mol of H₂SO₄