Allay, Alley & Ally

Allay means to make something less severe or strong: “Balms can allay pains in the body.”
Alley refers to a passageway, a narrow thoroughfare, narrow back street: “There was a busy street in front of the house and an alley behind it.”
Ally refers to associate, partner, friend; collaborator: “The United States was an ally of Great Britain in two world wars.”