The Pharaoh Zombie is unbelievably tough. Along with the tough Camel Zombies, they could kill your plants easily.
Upgrade your plants' level by playing previous levels. Then upgrade them more with Puzzle Pieces and the Oven in your house.
Drag as many plants as you can into the lawn. Use other users' plants to have even more power. Note that you should place the plant with the strongest attack in the middle lane, to destroy the Pharaoh Zombie quicker.