In a story about the Das Family and their taxi driver while on vacation, do you believe Jhumpa Lahiri constructed a hopeful story? Or otherwise?

I believe that the ending of the story is hopeful and that Jhumpa Lahiri was actually trying to create a hopeful ending. It may be argued that it is a depressing story with a sad ending but there are several instances in the story which will make the reader think that it is indeed a hopeful story.
One of the most notable instances is the ending; Mrs. Das shows through her actions that she does care for her family, that she loves Bobby even though he is not Raj's son and was never intended to be born. This act of affection from Mrs. Das towards her family is a proof that it is a hopeful story. At the start of the story she is confined to herself, she does not pay much attention to any of her kids, has her glasses on at all times as if hiding guilt under them. But at the end she gets out of the car without putting on her glasses, this is a big step toward getting more involved and attached. Also she is worried about Bobby; all of this show that she is trying to change and that she is becoming a person who cares a lot about her family. It is seen that towards the end she is willing to help Bobby. The fact that she wants to change to become a better human being is an indication that it is a hopeful story.
The monkeys who are usually known to be wild and uncontrollable become silent and calm towards the end. This is an unusual behavior and therefore cannot be overlooked. Perhaps they are portraying the feelings of the Das family at any given time. At first they are loud and frustrating like the feelings of guilt inside Mrs. Das but later on they are silent and calm probably like Mrs. Das who has started to realize that her pain is really guilt and therefore her pain has decreased.