Namaste Neha,
It’s very natural for a body to change after pregnancy, body has been preparing for the baby for all 9months, it has changed through this process so that it can support the whole birthing process
Nevertheless, she can start with postnatal classes with the teacher who has an expertise with prenatal postnatal yoga,
But firstly, she must gracefully accept the body and truly appreciate it , she can start with a guided meditations to connect with her body , slowly move to basic asanas which targets pelvic floor muscles in priority
Keeping an easy goal n being consistent would really help. One step at a time
Hope this helped:)