Final answer:
Walter's adoptive mother does not match any of the given choices. The descriptions provided from various contexts suggest that his mother's experiences are unique and do not align with the specific options provided for selection.
Step-by-step explanation:
Based on the given contexts, the best description of Walter's adoptive mother would not fit neatly into any of the provided choices. Instead, his adoptive mother appears to be an amalgamation of the experiences of several different women. Importantly, none of the women described exactly match any of the given options for Walter's adoptive mother. For example, Nella Larsen's mother was an immigrant mother and a Caribbean father, which is not reflected in the choices. Frederick Douglass' mother, Harriet Bailey, had a dark complexion and was separated from her son early in his life, which again does not align with the provided choices. The mother depicted by Jane Austen had six children and a good constitution, and the trials Matilda faced in her quest to find her son during wartime are also distinct narratives that do not correspond to the options given for Walter's adoptive mother.