What happens if the stock closes at exactly 17 at expiration?.
I doubt the put purchaser will choose to exercise at this price, but they have the option to do so. On the call side, it is in your power to exercise or not. Personally I would exercise it, because the stock typically goes up a little after expiration Fridays, but you take the risk that it opens down on the following Monday by doing so. The safe thing is to let it expire, although you'll likely find out on saturday you no longer have any position.
HailMary