Cleo de Nile and the Creeperific Mummy Makeover is the fifth and final book in the Monster High Diaries book series.
The de Nile family are dining together when Ramses receives some startling news - Dedyet, his wife and Cleo and Nefera's mother, has suddenly reappeared. Cleo, who has fond memories of how glamourous and elegant her mother was before they were separated, is delighted by the news. The next day, she tells the news to Frankie, Draculaura and Deuce, regaling them with tales of how fantastic she was, and announces that her family will be throwing a huge party in a few days to welcome her mother. Draculaura wonders if Cleo's mother might be different from how she remembers her, but Cleo is certain she'll be just as she last saw her. During the conversation, Frankie accidentally rips her skirt, and Cleo offers to help her repair it.
The next day, Dedyet de Nile meets the family at long last, but everyone, Cleo especially, is surprised to see her wearing a worn shirt and jeans, and no make-up. Even more surprising, she makes a snack for herself in the kitchen without waiting for a servant.
Dedyet explains that after the family escaped from their home in Egypt, she found herself in a hideout, waiting for word from her family. With nothing to do, she took to reading from a massive library, and developed an interest in archaeology, as well as becoming less accustomed to the lush lifestyle she had once lived. When she eventually made her way to the Boo World to find her family, she decided to spend some time assisting at an archaeological dig. Before they could finish though, they were trapped inside a tomb, and were only released recently.
Although impressed by her mother's tales, Cleo is worried that she and her mother no longer seem to have anything in common, as well as what her friends will think when they realise Dedyet is nothing like she had described. When her friends ask about her the next day, Cleo doesn't give out the full details of her mother's new look. After helping Draculaura with a new cherleading routine, Cleo hits on the idea of giving her mother a complete makeover at a spa, reminding her of how she used to be.
After school she meets Clawdeen, and asks if she could make a dress for her mother to wear for the party. Clawdeen explains she'd love to, but she's currently busy trying to design a dress for Clawdia, and can't find the fabric she needs. Upon seeing the design for the dress, Cleo remembers that she has a similar dress in her closet, and offers to give it to Clawdeen to modify into her design. The two head to Cleo's place, where Dedyet asks if she can meet Clawdeen. Cleo suggests that it would be a good idea to have a makeover so she can look her best before she meets her friends. Dedyet states that she truly is happy with the way she is now, and is disappointed that Cleo doesn't seem to understand. Cleo realises that she genuinely is happy that her mother is happy, and apologizes for suggesting the makeover. The two spend the night watching movies together, and reminiscing over Dedyet's stories of her time as archaeologist.
Realising that her mother probably wouldn't like the extravagant party she had planned, Cleo decides she needs to tone it down, despite Nefera's protests. She asks her friends for some help arranging the new party, telling them the truth about her mother's current look. Every one agrees they're sure to like her when they meet her, and Deuce is happy that he'll finally meet a member of Cleo's family that will actually like him.
Some time later, and with some reluctant help from Nefera, the party is redesigned as a 'come as you are' party. Dedyet meet's Cleo's friends, and Cleo asks if they're amazed by how different she and Dedyet are now. Her friends state that Cleo and Dedyet do have one thing in common - both of them are incredibly caring and willing to help others.
Dedyet's story about how she became trapped in a tomb during an archaeological dig is probably the explanation as to why she was found in the Catacombs in Hexiciah Steam's diary.. But while in the diary she was found by Robecca and her friends, in the book she escaped the tomb on her own.