Tough choice actually, but i'd go with (C), leaves us either Reimu, Souichirou or Ayu idle and up for defense. Can we rely on Wriggle/Mystia to DoW us? And if so, could our sole defender handle it?
We can't lose the shrine in a single attack if i understood correctly, so it's pretty safe to see if we can avoid wasting an action on DoW.
We can still go on the offensive ourselves on the next turn. Doing so now would kinda waste the partial Res from last turn (it doesn't go anywhere, but the point of choosing it over chat was getting to double up on Res later.).