If the top eight seeds make it to the quarterfinals, then who, among the players listed below, would definitely not play against Maria Sharapova in the final, in case Sharapova reaches the final?

If the top eight seeds make it to quarterfinals, then from the table we can find that Sharapova being top seed will meet seed 8 in the quarterfinals, and in the semifinals she will meet the winner of the match between seeds 4 and 5. So she will not meet seeds 4, 5 or 8 in the finals.
We can sum up the given information as below:
(ii) No team plays against the same team more than once
(iv) No ties permitted.
As per the information given for stage I, we can conclude and draw the table that
(a) As B lost at least one match, hence A won all the 3 matches.
(b) The two teams who lost all the matches cannot be A (as it won all 3 matches), cannot be B (since it is given that E lost to B), cannot be D (since D won against C & F). Hence, the two teams must be C and F.
(c) F did not play against the top team (i.e. A).
We can tabulate all the information as :
In the given below table a blank space means there was no match in this stage (i.e there was no match between A and E in this stage), Result of a match for a team is shown in its row,
(d) A lost both its matches against E and F.
(e) F won against A, hence is the bottom team (out of C and F) which won both the matches F won against C as well. This also means that C lost both its matches against B and F.
(f) Apart from A and C, one more team lost both the matches in Stage-II. That team can neither be E (since A lost to E), nor B (since C lost to B), nor F (as F won both its matches). Hence, the team must be D.