Final answer:
In the context provided, "matriculated" means that the person’s father enrolled him in school shortly after his birth.
Step-by-step explanation:
The term "matriculated" in this context refers to option (b) Enrolled him in school. Matriculation typically means the process of entering a university or college but can also refer to being registered or enrolled in any educational institution. In the historical sense, the term could also relate to a boy being registered as a citizen or entering into manhood, such as in ancient Rome with the donning of the toga virilis. However, in the context given by Mrs. Pennyweather, it is most likely referring to the formal registration of her son into a school setting shortly after birth.