Noveria is the planet covered in Snow, and has Matriach Benezia. In order to get the garage pass you need to help Lorik. Go to the garage, kill the Geth, and drive up. Once in the facility, you'll need to activate the VI's core. Either doing the Tower of Hanoi puzzle [search in the site or google for how to do it] or sacrifice 100 omni gel. Then, activate the power and landlines. Once in the tram, you must kill the Rachni, but first go down the elevator to where the survivors are at, get the pass, and to the hot labs. Activate the Purge and get out. Return to the survivors, (SPOILER: Kill them). Go to the end of the place, and go to the tunnels. Find the Matriarch. To kill her, you MUST kill the Geth and Asari Commandos. DO NOT FIGHT HER. Start off, kill the Asari Command rushing you, then RUN TO THE RIGHT and kill the Geth and Commandos after talking with her, she'll go berserk again. Kill ALL enemies, then kill her.