Here is the full list of all 20 Arkham Horror: Mother's Embrace achievements.
Use the same investigator for every scenario of the game
Save Arkham from the Dark Young
Kill the Dark Young with a Birthling explosion.
Commit suicide by smoking a cigarette
Find the recipe in every scenario
Completed "A Morbid Dance in the Second Line"
Steal Lanuit's trinket from his store
Completed "Tendrils of Witchcraft"
Have 75 items in your Office Chest at one time
Completed "Unwelcomed Guests"
Visit a Outhouse
Kill 3 opponents in a single investigator's turn
Completed "The Peculiar Monsieur Lanuit"
Completed "Herd of Algedi"
Completed "What Was Lost is Never Found"
Heal enemy with a Wild Cast
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"