Goodwife Cruff was shocked that Kit jumped in the water and did not drown.
The detail to remember is that Goodwife Cruff did not approve of Kit’s actions. Kit jumped into the water after Prudence’s doll. This would have been considered scandalous, because the Puritans did not swim. A person who could swim would be considered a witch. Kit would have been expected to drown there and then.
Goodwife Cruff would have been shocked and horrified when Kit jumped into the water when Prudence dropped her doll. The fact that the doll was important to the child would not have had any effect on her. She was not the sympathetic mother type.
Kit has no idea of any of this, until Nat explains it to her.
Kit wrinkled up her nose. "Ugh," she exclaimed, "that sour face of hers will curdle my food."
Nat laughed shortly. "'Tis certain she expects you will curdle hers," he answered. "She has been insisting to my father that you are a witch. She says no respectable woman could keep afloat in the water like that." (Ch. 1)
Kit and Goodwife Cruff do not get along. You can tell that Goodwife Cruff is a harsh woman. She does not really want her daughter to have a doll in the first place. It was given to the girl.
Goodwife Cruff would have been unhappy about watching Kit. She says herself that she does not like new people.
Goodwife Cruff halted and glared at Kit. "I'll thank you to let my child alone!" she spat out. "We do not welcome strangers in this town, and you be the kind we like least." Jerking Prudence nearly off her feet, she marched firmly up the dirt road and disappeared in the fog. (Ch. 1)
To Goodwife Cruff, Kit is dangerous. Even without jumping in the frigid water, which must seem crazy, Kit wears fancy dresses and is too spunky for a girl. She does not behave properly. She also fraternizes with the sailors. For all of these reasons, Goodwife Cruff does not want Kit near here daughter. She fears that some of Kit’s impious ways will rub off on her daughter.