The key phrase in the question is skewing the balance between finality and judicial review, so the task is to find which case actually expanded judicial review beyond what the Model Law intended.
Since the second case is the one that widened judicial review at the expense of finality, the correct answer is ONGC vs. Saw Pipes Ltd.
Another useful check is the aftermath of each ruling, since a decision that truly upset the finality-review balance would provoke a legislative correction, which is exactly what happened here.
Since only the second case's effect on the finality-review balance was significant enough to require a corrective 2015 amendment, the correct answer is ONGC vs. Saw Pipes Ltd.