Final answer:
To change a masculine noun to a feminine noun, replace 'widower' with 'widow' and 'father' with 'mother' in the sentence.
Step-by-step explanation:
To rewrite the sentence changing the masculine noun to the feminine, we can replace the word 'widower' with 'widow'. So the revised sentence would be: 'That widow is the mother of six sons'.
Learn more about Rewriting sentences with masculine nouns to feminine nouns