When people find out that Ms. Strangeworth is the culprit behind the insulting letters; she gets a letter herself, just like her own and it says " Look out at what used to be your roses". Showing an example of symbolist the symbol being the roses, while it represents her reputation in the town.
The baby represents innocence. the baby represents a legacy, a future. Ms. Strangeworth's letter saying "Didn't you ever see an idiot child before?[..]" makes fun of a families legacy and future.
Ms. Strangeworth represents society, always watching what other people are doing. Society doesn't know what it is doing. Making observations about your life and jumping to conclusions way too fast.