I’m sorry but isn’t this on the town itself? If land use restrictions are preventing them from having a second grocery store, then change the law. Monopolies will act like monopolies and its up to the local government to do something about it.
This could be solved today by not imposing arbitrary restrictions on what other people can do with their land without their consent.
That said, government policy could be more proactive in disallowing those sorts of restrictions and punishing companies when they try to impose them.