Apostrophe ???

[Unregistered]

Hi


He is not able to provide a better guess than Mary's as to who might be the winner.

or

He is not able to provide a better guess than Mary as to who might be the winner

 

[emsr2d2]

Hi


He is not able to provide a better guess than Mary's as to who might be the winner.

or

He is not able to provide a better guess than Mary as to who might be the winner

I would say both are possible. In the first, it is saying:

He is not able to provide a better guess than Mary's (guess) as to.....

In the second:

He is not able to provide a better guess than Mary (is able to) as to.....