How do I build house 4/4, a gold looking token is required how do I earn this to build my final buildings?

You need to take the third box reward on the event to get 20 tokens..

I see the same gold token looking icon in the requirements however I think possibly this is a coin icon and represents money. . The only requirement for building the house once you have reach the appropriate level for it (base level 10) is 70 Money.