Who observe the blood stains? What did they do afterwards? What did the house keeper tell them?

What chapter are you referring to?

mrs otis observed the stains and said that she didnt cared for blood stains in the room and that it must be removed.

as soon as mrs otis finished, mrs umney said that these stains couldnt be removed as it is the blood of Lady Eleanore de canterville who was murdered in that very spot by her husband . that blood stain has been admired by many tourists.

then washington (elder son) said that all of this was nonsense . he took a pinkerton detergnt , fell down on his knees at that instant and cleaned the stain .