Miss Fazakerley had spent the day with her family, and when she returned to the home the blanket had disappeared.
"The door was closed and it had a slip-bolt on the outside. So anyone could have gone in and taken it - but they would have had to have known what they were doing," Mrs Fazakerley said.
Her daughter had had the blanket since 2007. It was given to her by a close friend who died in 2008.
"She was always fond of that blanket, and it was special for her. She always had it on her bed," Mrs Fazakerley said.
She said Miss Fazakerley was quite angry about the theft. Mrs Fazakerley spoke to Laura Ferguson staff about it, and they reported it to the police.
Now Mrs Fazakerley is appealing to whoever has taken the blanket to bring it to the Whanganui Police station so it can be returned to Miss Fazakerley.
"Whoever did this was a real low-life. It was a lousy thing to do. It doesn't mean much to anyone else, but it means a lot to Naumai."
The blanket is for a single bed. It is silver satin with burgundy roses and green leaves on it.