The right option choice is option (C)
Remember usually when you see "more" in the sentence it indicate "comparison".
Here in the original sentence it indicates "degree" of something.
Hence, if you try to understand the meaning of the sentence you'd realize that the company as a result of low success on car ads, realized that they need to spend more money on banners. Please see below the process of elimination:
(A) that the company had to invest
more in marketing the car ads
as well as bundle banners and car ads into a single package-
WRONG(B) so that the company had to invest more in marketing the car ads and bundle banners as well as car ads into a single package-
WRONG-the company didn't do anything with some intention here. What follows in the underlined portion should reflect the result of what preceeded.
(C) so that the company had to invest more in marketing the car ads and bundle banners and car ads into a single package-
CORRECT(D)
as to forcing the company to invest in marketing the car ads
as much as in bundling banners and car ads into a single package-
WRONG- there is no idiom like as X as much as Y- the sentence follows this structure
(E) that the company had to invest in marketing the car ads
as much as in bundling banners and car ads into a single package-
WRONG - this distorts the intended meaning by saying "as much as"