What does it mean if an action is "of no avail?

In the reading, i know why the caged bird sings, marguerite views mrs. flowers as a larger than life personality. which quote from the text most strongly supports how marguerite views mrs. flowers? question 18 options: a) “i’ll accept no excuse if you return a book to me that has been badly handled.” b) “you see, i had planned to invite you for cookies and lemonade so we could have this little chat.” c) “there was a little path beside the rocky road, and mrs. flowers walked in front swinging her arms and picking her way over the stones.” d) “somehow i had never connected mrs. flowers with food or eating or any other common experience of common people.”