If there is a payment in USD then you would use 2 (whether the payment is relating to money market hedging is of no relevant – any payment of USD would be converted to Pounds using 2)
If there is a receipt in USD then you would use 3 to convert to Pounds.
I do suggest that you watch my free lectures on foreign exchange risk management. I spend time discussing which rate to use (and why), and obviously also go through money market hedging in detail.