In order to determine what she would have been thinking, I think it is best if you consider what her different actions might mean. That should help you determine what to say.
For example, the text says:
Just as Mr. Summers finally left off talking and turned to the assembled villagers, Mrs. Hutchinson came hurriedly along the path to the square, her sweater thrown over her shoulders, and slid into place in the back of the crowd.
This is our introduction to Tessie. She slides in late, hurriedly, and with a sweater in June. These details could mean she wasn't really clear in the head that day, they could mean she forgot about the lottery, it could mean she was trying to get a chore done before she went to the Lottery because it would take a long time... that might be what the sweater is for, it's going to go into the evening. Consider commenting on her planning how she was going to get there and work this event into her day.
She says she was doing the dishes, and she makes jokes. Why do people joke in times like these? Is that showing her nerves? Is it showing that she doesn't really believe it could happen to her at that early stage of the game before their name was drawn?
When it is their turn, Tessie makes a joke again and gets the crowd laughing. She encourages him to "get up there" and get going with this duty.
As the story continues, her actions change. Before she even wins the lottery, she begins to yell at Mr. Summers... that must show something about how she was feeling. What do you think it means?