Here is the full list of all 20 Arkham Horror: Mother's Embrace achievements.
Have 75 items in your Office Chest at one time
Completed "What Was Lost is Never Found"
Commit suicide by smoking a cigarette
Heal enemy with a Wild Cast
Save Arkham from the Dark Young
Use the same investigator for every scenario of the game
Kill the Dark Young with a Birthling explosion.
Find the recipe in every scenario
Completed "A Morbid Dance in the Second Line"
Steal Lanuit's trinket from his store
Kill 3 opponents in a single investigator's turn
Completed "Tendrils of Witchcraft"
Completed "Unwelcomed Guests"
Visit a Outhouse
Completed "The Peculiar Monsieur Lanuit"
Completed "Herd of Algedi"
Use a Radithor on an investigator without any Conditons
Completed "Finding Meaning in the Stars"
Use a Bromo Coffee when you Action points are full
Completed "An Invitation"