While McGarrett (Alex O'Loughlin) and Dano (Scott Caan) are dealing with a terrorist plot, they find out Deb's in jail. "I needed some grass," she tells McGarrett from her cell, "so how was I supposed to know the guy was a narc? I wouldn't even be here if it wasn't for those fascists at the dispensary. They wouldn't take my card. The guy behind the counter told me where I can find some and then I run into this narc."
So it would appear that Deb, played by the 80-year-old comedy legend, has a recommendation in California that's not accepted in Hawaii, hence her comment and search for black-market weed.
McGarrett has no idea that his aunt was suffering from an inoperable brain tumor.
Deb decides to medicate herself rather than go on a chemotherapy regimen. We never see here smoke, but by the of the episode she belts out a swell version of "I Got the Sun in the Morning (and the Moon at Night)."