(a): Inadmissible.
801(d)(2)(E) the statement must be in furtherance of a conspiracy. Here, he's just telling his girlfriend, so whether he's refering to the robbery or not, it's not in furtherance of the ocnspiracy.
(b): Admissible.
Here, assuming Ray knows of the robbery, it's in furtherance of the conspiracy. (But see (c))
(c): The paragraph after 801(d)(2)(E) states that the statement alone is not sufficient to establish the existence of a conspiracy or the participation therein of the declarant. So those things must be established by corroborating evidence, if it is to fit the hearsay exemption.