IB is very difficult - but it can happen at any.
The obvious answer is IU - but it’s still going to be a struggle - and btw - most have no idea what IB is - and the grind and change anyway.
I’d likely go Ohio State next and then Elon who punches above its weight career wise.
Then Fordham based on proximity and then Bentley - which has wonderful career outcomes.
Why don’t you ask each school for their outcomes - and you can see on your own.
It’s more than this though - it’s fit - Ohio State is massive, IU big, Bentley focused (what if he has other interests), Elon smaller with not as much around in the immediate area, etc.
Where will he fit best?