Final answer:
Justine had been out all night because she was looking for the missing William and took shelter from the weather, as depicted in Mary Shelley's novel Frankenstein.
Step-by-step explanation:
The question "Why had Justine been out all night at the time William was murdered?" relates to the plot of Mary Shelley's novel Frankenstein. This is a common inquiry in the study of English literature, particularly within the context of character analysis and understanding the events of the novel. It's important to note that the text excerpts provided do not pertain to Justine's narrative in Frankenstein but rather describe different scenarios unrelated to the question asked. In Frankenstein, Justine, who is later wrongfully accused and convicted of William's murder, was out the entire night because after searching for the missing William, she sought shelter from the inclement weather. When she returned the next morning, she was held and tried for the murder she did not commit.