In the context of Anne Frank's life and her diary, "The Diary of Anne Frank," it is Anne's mother, Edith Frank, who buys clothes for Anne and her sister Margot. Anne's diary provides a detailed account of her life while in hiding during World War II, and it often includes descriptions of her family's efforts to maintain some semblance of normalcy under difficult circumstances. Given the conditions of the time and the fact that the families were in hiding, acquiring new clothes would have been challenging, and they might have relied on helpers or had to repurpose or mend the clothing they already owned.
During the period that Anne Frank's diary covers, the Franks were in hiding from the Nazis in an annex behind her father's business in Amsterdam. Life in the Secret Annex, as they called it, required them to be as self-sufficient and inconspicuous as possible. This meant that shopping for new clothes would have been a complex and risky activity. As such, the families had to be very cautious about acquiring new items, and the task would have been carried out covertly, possibly by one of the non-Jewish helpers who were aiding those in hiding or by being done very discreetly. Clothing at that time was not just a matter of fashion; it was often rationed, and Jewish people had severe restrictions on what they could purchase, which is why this would have been a significant challenge during their time in hiding.