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