If you don't get anywhere with the local cemetary, try the Local Council of the area she lived, you never know what records they may have, but they might be able to point you in the right direction at least

I was very sad when I discovered there was no headstone but when I thought it through I realised there was probably no money for it. Grandpa died in 1942 and my sister in 1946, therefore during and just after WWII, so headstones were probably not at the top of any wish list.
I placed some flowers on the grass, said a little prayer and had a chat to them both, which sounds mad, I know, but it helped me to know I had found them and they are not forgotten by the remaining family.
I do hope you find what you need, and maybe visit the grave at some point.