Empty Nest Syndrome
It sounds as if your mother's sense of self has been based on her role of "mother," and that it is time for her to forge a new identity directed towards herself, rather then externally towards others.
It would be great if she would commit to doing a physical Kundalini Yoga and Meditation practice on a daily basis. Re: Meditation: Please explain to her that we all have to "walk in the mud, before we walk in the light" and that whatever thoughts and feelings come up during the meditation are part of a necessary clearing process which will lead to greater lightness and happiness in the long run. Meditation will help her to gradually get off her medication and learn to be more in the present to see new doors opening and new possibilities beckoning.
We recommend the Sa Ta Na Ma meditation which is on our Yoga Quick Fixes and Yoga House Call DVDs, the PM yoga set as well as both meditations on our AM/PM Yoga DVD, and the meditation in the Delete Depression on Yoga Quick Fixes. We also recommend all of Fat Free Yoga, In fact, if she had to do one thing, we would recommend Fat Free Yoga, as well as the meditations on it.
Two more suggestions: Maybe you can set up a Skype system and visit with, and even do a meditation with your mom on a regular basis. Encourage her to interact with people even if she doesn't feel like it. If you know of any other women whose kids have all left the "Nest," it would be great if she could connect with them for processing and moral support.
Overall, our advice to your mom would be to focus on new beginnings rather than an "end." We know that changes like these are easier said than done, but just by creating an intention and taking small steps, she can begin to make great progress.