Coffe egrounds are slightly acidic which would be good for most evergreens but arbs are the odd evergreen that doesn’t prefer acidic soil so the coffee grounds will not benefit your arbs.  While coffee ground are slightly repellent for deer, the effect is so brief that I’d not count on it being very effective.  Deer tend to nibble foliage and bark so some coffee grounds on the ground below won’t do much.  You’re better with a repellent spray like Bonide’s organic Repels-All spray.  http://www.bonide.com/trusted-brands/repels-all/