You can see in the first and second paragraphs how she feels at peace (or rested).
Then take a look at the third paragraph and notice how this feeling is starting to inspire her.
I believe the answer you are looking for here is 'inspired'.
This is a hard one and I can see why you decided to post it here. B is most definitely wrong but the other three are all neck and neck. There are both even pros and cons of A and C but I think it would be more reasonable to adopt a general routine. So I think the answer would be C.
Answer:
We haven't forgotten yesterday's picnic.