Car makes loud humming/whistling noise from under the rear by fuel tank/pump then car kills.

Could be the fuel pump. Any fuel leaks? If so, stop and see a qualified mechanic.
Is the sound coming from the rear of the car? Open the gas cap and listen at the fuel intake. Is the sound louder? If so, the fuel pump may have a rotted line attached to the fuel pump in the tank.
If he sound is coming from the dash or under the hood it could be a number of other issues.

A humming noise in the gas tank is usually a failing fuel pump.
The pump uses liquid gasoline to keep it cool and lubricated.

The problem you are discribing could well be the impending failure of the fuel pump I am assuming that this is a late model fuel injected car . The noise is transfered by the fuel in the tank . Have a tech check and make sure you have only a small amount of fuel in the tank when getting the pump replaced as the gas tank must be removed in order to replace the pump . Hope this is some help
Regards

Sounds like a lack of oil in the rear axle. have the rear end oil/grease changed...good luck

Sure wish I had a little more information, I could give a more detailed answer.
The fuel pump is in the fuel tank. Often it makes a little humming noise and if the pump starts to go bad, the noise can get quite loud.

Yes, this is indicative of fuel pump failure. It will need to be replaced.

SOUND LIKE FUEL PUMP.CHECK PUMP PRESSURE BUT MOST OF THE TIME WHEN FUEL PUMP GOING OUT YOUR HEAR HUMMING OR LITTLE WHINING NOISE.FUEL PUMP MOTOR BEARING WORN OUT.

under the car near rear end, fuel pump is inside the fuel tank

Sounds like a fuel pump causing noise. If the noise is still present with the key off then the fuel pump relay is stuck causing the battery to die.

There's several ways to check the pump and none are really difficult. First, make sure the car radio is off and there is no loud background sounds. Turn the key to the ON position, but don't crank the motor. There should be a humming sound coming from the gas tank. The hum is only about 2 or 3 seconds long, so be ready to listen.

If there is no hum, check the fuse under the dash. It's labeled "FP/INJ2" If the fuse is not blown, check the fuel pressure valve on the intake manifold. It's located under the injection plant towards the back of the manifold. Have someone crank the engine as you operate the valve.

If there is no fuel there, there is an inline fuse located SOMEWHERE under the body of the car. If the pump gets too hot, it will blow to save a potential fire. (I discovered too late that the in tank pumps can overheat if they are not submersed in gas. Keep the tank over 1/4 tank to make sure this doesn't happen)

If all fuses are good, but the pump doesn't hum, the pump is dead.

I hope this helps you out.