(a) No. In this case there is no offer made by A to C. A's offer is clearly made to B and to B alone. In such cases only B can accept that offer and make a contract with A. C's attempt to accept A's offer is best construed as an offer by C to A, to buy A's wine for $2,000.
This is not to say that it is impossible to make an offer to 'any person in the world at large'. If an offer is intended to be made to any person who learns of it, then of course any such person may accept the offer on the stated terms. But that is not what A has done in the present case.
Carlill v Carbolic Smoke Ball Co [1893] 1 QB 256 is an example of an offer intended to be made to any member of the general public.