Final answer:
Augustine's mother, Monica, and his son, Adeodatus, are the correct answers to fill the blanks in the statement about who in Augustine's family died before they could return to Africa.
Step-by-step explanation:
The blank spaces in the sentence 'Both Augustine's mother and son died before returning to Africa' should be filled with 'mother' and 'son' respectively. Augustine's mother, Monica, died in Ostia, Italy, as they were preparing to return to Africa after Augustine's conversion and baptism in Milan. His son, Adeodatus, who was highly regarded by his father for his intellect and abilities, also died early at the age of 17 in Africa, not long after Augustine had taken up his position as a priest. These events were profound in Augustine's life and influenced his future theological contributions to Christianity.