Maybe I'm stupid but if
The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did NOT save.
And she did not save 9 per month where she received 12 then 3x9=27 but according to your calculation she saved 36 and not 27. that means C can't be the answer unless i'm completely wrong.
alice's every month take home pay = 12 (just picking random suitable number)
alice saves per month=12*(1/4)=3
alice does not save per month = 9
1 year =12 months
so for the whole year she save = 3*12=36
so for the whole year alice didnot save =9*12 =108