By using the context, we can determine that the meaning of the word "futile" in "Marigolds" is "fruitless" or "pointless".
"Marigolds" is a short story by Eugenia W. Collier (born in 1928 in Baltimore). This is where the word "futile" appears in the story:
<em>"I suppose that </em><em>futile </em><em>waiting was the sorrowful background music of our impoverished little community when I was young."</em>
What the narrator, Lizabeth, means is that is was pointless<u> to wait for things to get better, for poverty to just disappear.</u>
The context and setting of the story is the <u>Great Depression</u>. Lizabeth and her family live in a very <u>poor neighborhood</u>, and things are only getting worse due to the <u>awful economic situation</u> of the country.
Thus, waiting seemed futile, fruitless, pointless. Nothing was going to change.