Complex sentence: When she returns the doctor and hotel staff insist that she arrived alone, they have never seen her mother, and when the daughter goes up to her mother's room, the furnishings and decor are different.
Split into simpler sentences: When she returns, the doctor and hotel staff insist that she arrived alone and that they have never seen her mother. When the daughter goes up to her mother's room, the furnishings and decor are different.