Grassy Path

Roundup/glyphosate. There's stuff that's longer-lasting but don't apply it anywhere that roots from nearby trees/bushes might travel beneath. Or, if you're worried about the bees (and, really, we should all worry about the bees), you can use a mixture of salt and vinegar with a touch of dish soap to help it stick. 1 gallon regular white vinegar, 1 cup salt, a tablespoon of dish soap. If you use 2 cups of salt, nothing will ever grow there again.

>>2161817
To fix the problem you need to dig up and redo the path. However it is easily treatable like>>2161892 said.

>>2161892
I have to advise against roundup or any other herbicides. In my experience, they're very hard to contain and will end up killing things downstream from where you apply them. The only thing to really do is tear out the stones and redo the path. You might try mulching it this time.

Salt will kill pretty much any plant "for good". Salt the surrounding earth

>>2162194
>this myth again
It's going to take a hell of a lot of salt, and that stuff will wash out in a few months.