Kate, I know that hopefully your getting help. But I just checked the trains from Amsterdam to Nijmegan and a return ticket is onl $33 Cdn to $55 Cdn (depending on class).
So you should be able to travel their quite economically. And then possible some short cabs from the train station to the Cemetary.
Just thought I'd post this, but your probably on top of it already.
I do wish you a great trip