Car rental agency names and locations

Google maps is pretty accurate.
Start with 'Auto Europe' and plug in the addresses.

This is the way I make sure we always have accommodations quite convenient to the rental yard,... especially important at drop-off time.

I have done the same as Bill. First to get a price quote through Auto Europe, then to use Google maps to find the street addresses that Auto Europe provides. You can also go to Google and make a search for "car rental near Nice, France," or other, similar search, to see multiple locations. Most towns of any size do have car rental, often walkable from the train station. There's normally no fee to drop a car at a different city within the same country, but there is a large fee to drop it in a different country.

When you get a price quote, the always ask you for the pick-up/drop-off locations and give you a list of the possibilities.

As far as names/websites, Google AutoEurope, Sixt, Gemut, or most US car rental agencies.