Which of the following statements is not correct with regard to inheritance under Sunni (Hanafi) Muslim…

Under Sunni (Hanafi) law, a brother's son (nephew) is a residuary, but a brother's daughter (niece) is only a distant kinswoman. The nephew therefore excludes the niece altogether; he does not take twice her share.

The other statements are correct. A son takes twice a daughter's share and a full brother twice a full sister's share when they inherit together as residuaries. A widower takes 1/2 (or 1/4 if there is a child), twice the widow's 1/4 (or 1/8).