In this scenario, since the rock is very hard and the drill needs to break it apart effectively, a percussion drill would be the most suitable option. A percussion drill utilizes repeated blows to break apart hard rock, making it ideal for this situation.
Additionally, since the groundwater is not too far below the surface and a suction pump can be used, a submersible pump would be effective for bringing the water to the surface, as it can operate below the water level and efficiently pump water up.
Therefore, the best option for the company to use is:
a percussion drill with a submersible pump.