Sometimes is very hard to tell someone that they are mistreating their pet especially if its a friend. I'm a part of a hamster owners community in my country and we deal with mistreatment daily.
The excuses ususally are: Pet shop person told them it is ok, vet told them it is ok. Hamsters are small so this 20 cm by 30 cm cage is fine. etc. These type of people will not change their behavior and will not improve.
Some do change and they get a bin and a wheel and start again but these are rare cases.
You could give her some youtube videos like: erinsanimals and Munchiesplace. Just say that you are inspired by these people and make sure you give the videos that talk about basic care.
