I want to know that what could be the main reason of high electric bill??
Is it due to AC's or refrigerators?
I use low wattage bulbs and they consume very less electricity.

Both ACs and Refrigerators, as well as heating and cooking appliances use an awful lot of electricity. Much depends on the application of the air conditioning...keeping it running all the time will certainly raise your bill.

Even if you're using low wattage bulbs, it's a good idea to turn off your lights when you're not using them. However, adjusting your thermostat so that it's just a bit cooler in the winter and a bit warmer in the summer will make more difference than any lighting adjustment.

Also, do you have an electric hot water heater? That can use a lot of electricity as well.

30% or more of the energy useage is due to heating and colling costs, i did a foam insulation and my July electric bill was 98$

I think you may want to look at all the stuff you have running. Such as the the pool's electrical system heating/cooling etc. The big one is probably the A/C.

ACs and Refrigerators are really one of the top reason why electric bills increase. Also appliances that are not in use should be unplugged.