Hello KMT24

I'm sorry to hear about the loss of your Grandmother earlier this year and that your Mum is struggling with her grief. 

I'm unsure from your post if you've spoken to your Mum about your concerns. People are often worried about saying the wrong thing but from your post I think it's important that you talk to your Mum about your concerns. It may be that she is still getting support from the counsellor but without asking you won't know. 
There's some really helpful information on the Cruse website about supporting someone who is grieving. I've linked it for you here. 

I'm sure that your Mum will be grateful to know that you are there to support her. 

Best wishes, 
Jenn
Cancer Chat moderator