Panic is a function built into some farm contracts that allows the vault to quickly withdraw all tokens from the farm contract in the event of suspicious activity. This is done as a precautionary measure to protect the funds from any malicious code changes that could be made to the farm contract. The time lock feature of the farm contract ensures that any malicious code changes will not be executed until the lock has expired, giving the vault time to withdraw all tokens before any damage can be done. This was demonstrated in the case of Monster Cash, where the devs made code changes on the last days of the project, but the vault was able to withdraw all tokens before any harm could be done.