Mrs. Van Daan objects to Anne and Peter spending time together because of her jealousy, influenced by the stress of the situation they are in. Therefore, option B is correct
In The Diary of Anne Frank, Act II, Mrs. Van Daan objects to Anne and Peter spending a lot of time together primarily because she is jealous that Peter is showing affection to someone else. While all of the given options could be potential concerns, her jealousy stems from a deeper sense of insecurity and the close quarters amplifying personal tensions. Mrs. Van Daan is not worried that Anne might write about Peter in her diary, nor does she explicitly fear that the young couple might run away or that Mr. Van Daan would disapprove. Instead, her objections are more visceral and personal, rooted in the complex emotions arising from their precarious situation of being in hiding during a time of extreme peril.