Final answer:
Dunstan's absence was likely overlooked due to the family being overwhelmed with grief from Basil's death and distracted by the ongoing war. Personal preoccupations of characters like Dexter with individuals such as Devlin also contributed to lacking awareness or concern about Dunstan’s whereabouts.
Step-by-step explanation:
The question 'Why did no one think anything of Dunstan's absence?' can be understood within the context of the particular story's dynamics and characters. In the given text, it is likely that the absence of a character named Dunstan didn't raise concern because the family was already overwhelmed with the shock and grief from Basil's death, as well as the constant tension from the war.
The family's focus was on survival and the hope that their loved ones would be safe; they closed their minds to the harsh realities to carry on. On a more personal level for other characters, like Dexter, the preoccupation might be due to other emotions or preconceived notions about different individuals such as Devlin, which indicates a potential distraction or a preoccupation with other matters.