Mrs Maudie is a widow and a gardener. she's attentive and caring towards Scout and Jem. The children admire her because she treats them like “friends”.
The line "A new sensation is the breath in his nostrils" is a metaphor (C). A metaphor is when two things are compared without using like or as. In this case "a new sensation" was being compared to "breath in his nostrils."
