Patient denial at the end stage

My sister B has end stage pancreatic cancer and is now in a hospice.  B wants to go home though this is impractical at this stage as her daughters, who she lives with, are already struggling to cope emotionally. I have asked her does she think the girls will cope when she actually dies at home as they have to live there after and she says "I think so". B thinks she has longer to live than the medical team suggest.  What on earth can I say to explain why she is in the hospice now? The medical team have told her she's in the final stage.  B is a strong willed, mentally astute lady who has not given up hope, just torture.