Answer:
It should be recommended that the customer should sell long.
Step-by-step explanation:
As the offer in the question is contigent on 64% of the tendered shares, this makes the tender be inappropriate if the customer wants to cash out the position.
The right step to take is by selling the long position that has a new higher market price.
Therefore, it should be recommended that the customer should sell long.
Note that to sell long implies that stocks or any other financial investment instrument are purchased now for the purpose of selling them at a higher future price in order to make a profit.