Read Nicki Doane's Response:
First and foremost, I would insist that she consult her oncologist before going to any yoga classes at all. After she has received the OK from her doctor, then you and she can figure out what will work best for her. This may involve private lessons for a while, or possibly figuring out a way of modifying certain poses so that she can still come to class.
The most interesting part of your query was your statement that her memories of the class making her feel good are what propelled her to return. It may be that the class, especially if it is a strong practice or vinyasa in style, will not make her feel better. If she gets nauseous or light-headed at any point, I would ask her to stop.
I teach a weekly restorative class, and that is the kind of class I would encourage her to attend. Start slowly and add a little bit at a time. If something doesn't feel right to her, it probably isn't.
Nicki Doane had a wanderlust that led her to India in 1991 to study yoga. She went to Mysore to meet Sri K Pattabhi Jois and immediately realized she had found her teacher. Nicki started teaching in 1992. She cites Pattabhi Jois, along with Eddie Modestini, Gabriella Giubilaro, and Tim Miller among her most influential teachers. She is an authorized teacher of Ashtanga Yoga. Although rooted in Ashtanga, Nicki's teaching goes beyond the traditional. Her classes combine asana, Pranayama, philosophy, and poetry. The emphasis is on awareness: creating integrity within each pose that can be carried beyond the mat into daily life. Nicki lives in Sebastopol, California with her husband, Eddie Modestini. Together, Eddie and Nicki co-direct Maya Yoga Studios in both California and Maui, Hawaii.