What does the idiom 'To grasp at straws' mean?

Correct option is B

Option (b) is the correct meaning of the given idiom.
Given Idiom: To grasp (clutch) at straws — In moments of crisis, to try any possible solution, however unlikely or feeble, out of desperation. (Hindi: तिनकों का सहारा लेना/आख़िरी उम्मीद पकड़ना.)
Example: “With the deadline hours away, he was grasping at straws, trying random fixes to revive the server.”
Other related idioms and their meanings:
· A Hail Mary — a last-ditch, low-probability attempt to save a failing situation.
· Last throw of the dice — a final attempt when all else has failed.
· At one’s wits’ end — so worried/perplexed that one doesn’t know what to do next.