And they lived happily ever after:
..except for Cathy, who—as fated from the very first episode of The Big C—died from her terminal cancer in “The Finale,” but met up with Marlene and Thomas the Dog in the afterlife and, we assume, lived happily ever after. Even Cathy’s hapless husband and formerly dysfunctional son, based on our last sightings of them, seem destined to be okay in the wake of Cathy’s death, which is all she ever wanted, even when her relationships with Paul and Adam were at their worst.
Even though The Big C was quickly summarized as “woman diagnosed with terminal cancer goes on zany adventures,” as the clock wound down on the series, it became apparent that, while Cathy Jamison was the main attraction and her death was the featured event after four seasons of buildup, much like death in the real world, the stories that seemed to matter the most were those of the family and friends Cathy left behind. While it was satisfying to see Cathy close the book on her mortal life, get the all-clear from her not-actually-a-real-therapist therapist, and enter Heaven (or whatever) of her own free will, that was the point in which we the audience couldn’t really relate and the fantasy elements that The Big C has often dabbled in took over. That’s not to call the idea of an afterlife—no matter what your own personal beliefs describe it as—a “fantasy.”
It’s just to say that it’s not the sort of thing anyone has ever come back from with a concrete understanding of what it is and how it works. The Big C itself seemed to try to throw up its own sort of internal disclaimer with Cathy’s frank discussions with the imam, rabbi, and priest—grilling the three authorities that represented the Big 3 in world religions about how their respective creeds described the afterlife and then representing it as something completely removed from all three interpretations.
From a practical standpoint, it was the easiest way to avoid being slammed as having an “agenda.” But from a storytelling standpoint, it gracefully answered the question that Cathy spent much of her final months asking: What’s next?