Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word:

You visit your mom who lives inside of a car. It's sad, and you feel bad. The first thing that pops out of your mouth is: "Cool Room, Ma (くるま) because you don't know what else to say about your ma's living situation.

Be sure to sort of cut off the last letters of the first two words... something like "coo' roo' ma!" Sad thing is, there is only one room in this car your mom calls home.