This can be done easily with the shotgun. If you are low on ammo, be sure to check the boxes and drawers in the area. During the boss fight in the garden with Marguerite, after putting enough damage on her she will begin running around like a spider. When she gets on the ceiling she will lunge at you, you must shot her with the shotgun while she is in the air. On the easiest difficulty you will survive getting hit by three lunges.
Here is a video guide with English commentary!
Here is a playlist of guides for this game!
https://www.youtube.com/playlist?list=PL-HeW6XkKdUKUtj7CV_kW...