Main clause, intensifying ........

"intensifying ..." is a modifier refers to previous clause.
expectations -> signals to use "would"

expectations of X -> X should be noun or noun phrase
expectations that X would do Y -> correct

a.) that personal spending in the July-September quarter more than doubled that of
->"that of" not required
->"doubled " incorrect

b.) that personal spending in the July-September quarter would more than double ->Correct

c.) of personal spending in the July-September quarter, that it more than doubled
->"doubled " incorrect
-> Comma before that makes the fragment

d.) of personal spending in the July-September quarter more than doubling that of
-> incorrect as explained above

e.) of personal spending in the July-September quarter, that it would more than double that of
-> incorrect as explained above

A is the correct answer

B is wrong because of redundancy.

since expectations is used, no need to use would.

I am with B.............

I am with B.............

Should be B..
As Akhil explained, we need to have 'would' over her and out of B\E. B does correct comparison