The "The Mole" can easily be obtained in the team modes Domination and Artifact Assault. You have to earn the most defense bonuses that you'll get by killing either targets that are at your base and trying to take over your base in Domination or simply killing targets that have stolen your beloved artifact in Artifact Assault.
The "The Sneaker" accolade is the easiest to obtain in Wolfpack mode when you're playing by yourself. Alternatively you can get it by getting revealed the least by your targets in Assassinate.
Hope that helped you out.
The Mole Accolade is having the most defense bonuses. To get a defense bonus: You have to play Domination, and kill the last attacker within a friendly base, when it is below 25%.
Basically, stay at one team point and wait until the attackers have over 75% of the space, killing the attacker should give you a defense bonus. If there are mulitple attackers, it will only count for the last one.
(This was also my last accolade that I had to get)