Thank you both. I'm realizing this was a much more serious issue than I first thought. I go back on Saturday, and if the patient is still there I'm definitely going to look for more information and discuss with the nurses.
I'm realizing this was a great opportunity to do further assessment. I had assumed
(bad, anashenwrath, bad!) that the family was trying to spare their mother. But there could be a variety of reasons they don't want to tell her, some reasons may even be not-so-honorable. But most importantly, it comes down to whether or not SHE would want to know.
Now, maybe she specifically said to her family that she never wants to be told if she's dying, but it was my job as the nurse to find that out. I should have first assessed the family and investigated why they don't want their mother knowing, then I could have provided teaching where necessary and clarified my obligations.
Ugh, I feel kind of gross about myself. Lessons definitely learned.