There are two main problems with the original sentence:
(1) The government authorities urged citizens to do three things: remain vigilant, report suspicious behavior, and take actions to speed up the recovery from an economic catastrophe. Consequently, these three requests from the government need to be parallel. In this case, each command should be in the infinitive form (e.g., to remain, to report, andto take). The original sentence wrongly constructs the phrase taking actions necessary to speed up the recovery from an economic catastrophe such that it modifies the two previous actions. Instead, this phrase should reflect the fact that taking actions... is a third action that the government is urging citizens to take. In short, the three actions that the government is urging are not parallel and they should be.
(2) taking actions necessary... illogically modifies the command to remain vigilant and report suspicious behavior because these two actions would not speed up the recovery from an economic catastrophe. In other words, it does not make sense that remaining vigilant and reporting suspicious behavior (two actions that would occur before an attack) would be modified such that these are actions that speed up the recovery from an attack.
A. The three actions that the government urged are not parallel (i.e., to remain is not parallel with taking); the word necessary is not needed
B. The three actions that the government urged are not parallel (i.e., to remain is not parallel with reporting and take)
C. The three actions that the government urged are not parallel (i.e., to remain is not parallel with reporting and taking); the word necessary is not needed
D. The sentence is correctly constructed as the three actions that the government urged are parallel; the un-needed word necessary is omitted
E. The meaning of the original sentence is distorted as this sentence indicates that the government asked citizens to be more vigilant in reporting suspicious behavior (a single command) while the original sentence separated the command to remain vigilant and the command to report suspicious behavior; the three actions that the government urged are not parallel