The noun is condolences: "Please accept my condolences on your loss." The adjective is condolence: "I sent the widow a condolence card." (At least in America, the more colloquial term for that is actually "sympathy card.")

It should be condolences. We say 'My condolences to you on your loss'

Condolences. We would like to extend our condolences to your family.