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