"Mother's umbrella" is incorrect in English. Correctly written as mothers' umbrella. The apostrophe comes after mother to imply possession. Mother's umbrella would literally read as "mother is umbrella". This of course makes no sense and therefore the question itself is incorrect.
This is incorrect. The correct answer is "Moms' umbrellas". By putting the apostrophe after mother it implies possession. Example. Mother's umbrellas is incorrect because it literally reads as. Mother is umbrellas. This is incorrect unless your mother is made from several umbrellas.
It should be written as.. Mothers' umbrellas because they are umbrellas in the possession of mother.