[concretebob]

Your spelling is correct according to my spellcheck
No, once the liquid has penetrated you can only remove it by removing the affected surface.
There are cleaning solutions for removing oil from concrete, but they don't actually "remove" it, only bleach it and carry it deeper into the surface.
Cement, being a man-made material, is suceptible to other man-made materials.
Granite is a natural material.
But anything that eliminates the visual appearence would be good.
The beauty of granite is that it is practically indestructible with solvents or acids.

[Icorps1970]

If its Hydrofluoric acid it will etch the stone according to
http://www.findstone.com/othprob.htm
Some will cause color changes.
If the vandal did research the monument may be permanently stained or etched.