I have a ceiling light/fan with red, black, white and green wires. The ceiling box has a black and neutral coloured wire. Which wires go where?

Red and black go together, white to neutral and green to the ceiling box which should be grounded from the supply. You only have 2 wires coming to the box? How old is the house?

I think it was built in the early 70s. Why are 2 wires a problem?

Black/red to black
White to white
Green to the metal box.

No problems.

Ceiling Fan Wiring, Ceiling Fan Wiring Technical Help, Do it Yourself (DIY) - Ceiling Fans N More

If there are only 2 wires there is no ground. If there is a white and black plus a bare, the bare is ground.