I’m assuming she’s not a baseball pitcher and, maybe not even a painter. But, most rotator cuff tears happen because of repetitive and/or usually forceful overhead movements. My guess is the tear was posture related, and, over time creating a significant muscle imbalance.
Focus on strengthening the postural muscles and stabilizing the scapula by strengthening the rhomboids, lower and middle traps. Most all upper body exercises should be extension exercises, try and stay away from pushing. However, there’s always an exception, strengthening the serratus anterior is a good idea too. When deciding on exercises, be aware of pain levels and the position and movement of the scapula…..
As Susan mentioned, see what her status was, if possible, just before leaving physical therapy.
Hope this helps.