The Question and Answer section for Tuck Everlasting is a great resource to ask questions, find answers, and discuss the novel.
In my opinion, they're thinking about the punishment Mae will face. At this point, they are grateful for the safe return of their daughter and thinking of little else.
Mae and Tuck have lived in their house for around twenty years.
Winnie considers how she once smashed a wasp and regretted it. Killing a wasp is not like killing a man but Winnie considers the violent act to be similar.