Are there any specific food to take and to avoid while in chemotherapy for breast cancer in stage 3. Age is 60 yrs and vegetarian.

Possibly. It depends on which drugs you are getting. Each drug has a slightly different effect on taste. In general you should maintain your nutrition. Plant based diet has been suggested to reduce the risk of recurrent disease.
Not really. If your cancer has the estrogen receptor, some oncologists advise avoiding soy, wild yam, red clover, and other phytoestrogens. There is conflicting evidence that these can cause breast cancer cells to grow more quickly. I advise patients not to add soy supplementation, but i think it's ok to continue eating soy if it's part of your baseline diet, especially if you're vegetarian.