As a mum myself with Cancer the only advice I can give you is to try and be as positive as you can with your mum. 

I like to avoid talking about it unless I want to. Most of the time I feel it is best to take my mind off it. When the grandchildren are here I enjoy their company so much I don’t think negatively and it makes me feel good. 

If your mum does want to talk about it remind her that these days there are so many success stories. New medications, trials , immunotherapy etc. 

I attend a hospice day unit once a week. We have art and craft activities, therapy sessions like reflexology, massage, nails done and the opportunity to talk to other ladies with similar problems. We laugh, sometimes cry but mostly laugh and have fun. Your doctor will put you in touch with one in your area. You can also get counselling for your mum and yourself.  Good luck x