Which is a better domestic fuel among the following?

LPG is a better domestic fuel.

Wood produces a large amount of smoke when it is burnt since it has a very low calorific value. So it cannot be considered as a better fuel. 

Coal is similar to wood. It also produces smoke.

CNG has a very high ignition temperature and is volatile in nature, so it is not used as a cooking gas. 

LPG has more calorific value than wood, coal, and CNG and it produces no pollution. So LPG is a better domestic fuel.