nurse calls her Aunt Phoenix. This is significantly more polite than "Grandma" because she has the courtesy to use Phoenix's name. The nurse does get frustrated when Phoenix doesn't answer her questions. The nurse scolds Phoenix, saying to her "Tell us quickly about your grandson, and get it over. He isn't dead, is he?" So, even though the nurse initially appeared kind, she quickly treats Phoenix like an annoyance. Rather than marvel at Phoenix's determination to help her grandson, in spite of her old age, the workers at the clinic treat her like a nuisance. 

The nurse gives her the medicine, adding "But it's an obstinate case." Here, the nurse implies that either the grandson's ailment is persistent or that Phoenix is stubborn for continually trying to make him better with the medicine. After trying to "hush" Phoenix, who has begun talking too much for the nurse's taste, the nurse does offer some money to Phoenix because it is Christmas. This flippant act of charity is slightly admirable, but it has come after a series of condescending comments and gestures. Those at the clinic agree to help Phoenix, but in subtle and sometimes overt ways, they treat her like a nuisance.