When my father died (the last of that generation) my sister announced dramatically ' We are orphans now'. I did not feel like that, I was just grateful that our parents had lived longish fulfilled and happy lives and had passed on much love and wisdom to us and that my DC had a full set of grandparents until they reached adulthood. My DGC are similarly lucky with a full set of GPs and I have made sure, via photographs and reminiscence that they are learning about their family history, their GGPs and why they have some of their middle names.
Your children have not had that grandchild/Granny relationship which is more than sad, but you can make sure that they know all about their Grandmother and how much she would have loved them'.
Locally, there are many organisations short of volunteers to help at lunch clubs, or befriend lonely elderly people. Perhaps if you volunteered in this way you would be rewarded by developing friendships there.
Also feel free to join in on Gransnet, we would be happy to hear your joys and sorrows and how your children are growing up. Do any of them resemble your Mum or share her talents and characteristics?