I have a house in Minecraft and since wood planks was the most abundant resource in my inventory, that is what I made it out of. I put a lava moat around my house for defensive purposes. My house keep catching on fire, how can I stop this from happening?
You can simply move your lava moat further away. This answer says:
Fire can also be born from lava. Fire is always created above the lava position. Fire can be created in a 5x5x2 shape above it
So you just need to move it about 5 blocks away from any flammable material.
Additional, you can build a wall of cobblestone or glass (any non-flammable material) around your house to protect it from the fire.
A resource cheap way, if you don't care about looks, is using water as a "shield" around your house. Pour it so it covers most of your house, except the door, and have it run down into a second moat. Have a border of dirt between your lava and water moat so the water doesn't put the lava out. This will not look top of the line, but will help out if your resources are limited. Iron is easy to come by, and water is too. This will also shield against creepers blowing your house up, if they ever manage to get close enough. And if you happen to fall into the lava moat by accident, you have water right there to put you out.