Miss prism's words an actions shows that she shows importance of social rules. Her recoiling from Jack and stating that she is unmarried is an expression that she cannot be embraced by the opposite sex so carelessly. Moreover, since she is unmarried, it would be impossible that miss Prism was his mother. Victorian social code frowns upon having children when they are not married yet.
Sanguine is the word that best describes a person who is extremely upbeat and optimistic. Reticent means shy, apogee means climax, and caveat means a warning.