I lost my mother to ovarian cancer many years ago, she was 54. The chemo was probably the worst part of the disease, yet it also offers the most hope to people who trust allopathic medicine. My thoughts matched grz's. I strongly believe carrot juice will prove a valuable asset in helping your mother during this time. It is nutricious, contains healthy sugars she needs to keep up her energy levels, and it is good for the liver, an organ that is very stressed during chemo.
Try a ginger-lemonade too. If you are open to using green tea, add that to the mixture. Brew some green tea and an equal amount of ginger tea. Add enough fresh squeezed lemon juice to give the tea a lemonade tartness, then sweeten with raw honey.
Have you mom eat all the brightly colored raw fruits and veggies she can. Eat them raw or gently steamed. In my mother's time the chemo would cause mouth sores so your mother may not feel like eating a lot of acidic foods. You will need to experiment, but foods high in natural anti-oxidants will be ideal during this time.
Try to get your mother outside as often as you can. Fresh air and filtered sunlight will help her physical and emotional health. Most of all, just be with her. No matter what the prognosis or the method of treatment, your mother wil need you just to be there and being as supportive as possible.
Perhaps you can learn some healing techniques that involve touch, Reiki, Quantum Touch, Trigger Point Massage and other modalities may prove to be of great help and comfort. Most of all it will help keep your mother connected to her family and she needs your love and healing energy so much.
I pray all will go well for you all. Chemotherapy has made a lot of advances since the late seventies and I hope the treatment will be more gentle and more effective than it used to be. I do no the statistics for recovery has improved over the years, so do not give up hope. When hope is lost, nothing else really matters.