Hi mugdha, good to know she’s ready for a makeover. Ask her to get a layered cut as shown in the link: https://planetzuri.files.wordpress.com/2015/03/best-haircuts-for-long-hair-01.jpg
And she can go for short hair later. It would be a huge step to loose waist length hair at once.
Try different hairstyles instead of getting short hair at once.