That is strange. Normally, you’d have 2, 2 and 3. A 2-wire feeding power, a 2-wire feeding the light and a 3-wire to the other switch. I have no idea how a 3-way would work without 3 conductors going to the other switch. You need one conductor to send power to the far side, and 2 travelers to send the toggled hot back. If the load was in the far box, it’s doable with a companian romex (usually for receptacles), but that’s not what you have.
If you are sure that the feed and the light 2-wires are correct, then just wire those two Romex as a simple 2-way. That gets you the light in the garage but you probably want one in the house too.
What you’ll have to do is trace that third 2-wire mapping the two conductors in the garage to 2 of the 3 conductors in the house box. Since you don’t know where those are going, the best approach is to tone the wires.
If you’re not familiar with toning, its basically where you use a small device to place a “tone” on the conductor and then go look for it using a probe on the other end. YOU DO THIS WITH THE BREAKER OFF!
Or, you can wait for this: