I don't think A & C are viable as the hand has started, player was at his seat (rule 29) and the hand needs to be completed. B is the answer.
Then, if the player is not found Robert's rules is pretty clear:
"If a player leaves the table for any reason and will return before 20 minutes are up, he can opt to drop every hand that occurs during his absence. He will be responsible for all antes and blinds and will be dealt cards. Players remaining at the table, or another person designated by the absentee, will post all antes and blinds for the absent player. If the missing player is moved to another table, his chips will move and he will continue to blind appropriately at the new table. Any player who does not return within 20 minutes forfeits all his remaining chips, and are removed from the table. There will be no refunds or cash-outs given to players who leave after the first hand of the tourney is dealt"
This is the way I would handle it, but we will see what other TD are thinking...