Are there medical issues preventing her from being able to eat? Is it depression?
The best way to help her is to let her know you are there if she needs anything, help keep her comfortable and pain free.
If the not eating and drinking continues, please contact a doctor.
I went through a bout of failure to thrive. I stopped eating and drinking. I also could not sleep. I dropped a lot of weight. The doctors put me on an antidepressant to help me sleep and eat. My Cancer has gone to stage 4 but I am doing better than I was a few months ago with stage three.
Alex