Mr. Middleton gives Mrs. Von Macht his spirit image; she's scared
Mrs. Von Macht calls over Horace; he sees Eleanora again
Horace and Mr. Middleton are giving Mrs. Von Macht her picture when Horace sees her dead daughter, Eleanora, in a floral arrangement. He becomes concerned because he never knew her in life and he believes her to be angry.
When Horace and Mr. Middleton give Mrs Von Macht her edited image showing her ghostly dead daughter next to her, she becomes scared. She calls Horace over to confirm that she is seeing a ghost.
I believe this scene is significant because it creates conflict within Horace against himself. Because Horace sees Eleanora, who is deceased, he starts to become anxious that she is vengeful and angry with him. I think Horace is scared because he is seeing Eleanora in places he shouldn't be.