He wrote the story with his friend's 'assistance'. = He wrote the story 'with the assistance of' his friend. [=his friend helped him to write the story]
Our family had to 'go on public assistance' [=receive money from the government] when my parents lost their jobs.
Nobody 'came to her assistance' [=nobody helped her] when her car broke down.
(..) - Yeah, Chris. - Yes, Mr. Ribbon... ...I would love to have the opportunity to discuss some of our products. I'm certain that I could be of some assistance to you. - Twenty minutes. Absolutely. - Just had someone cancel. I can give you a few minutes before the ers. - Monday Night Football, buddy. (..)2006 The Pursuit of Happyness