I think it wasn't just pure chance that they found the laundrymat. The name of the street where the laundrymat was located, as printed on the bottom of the card, looked like it was the same as one of the two streets that Jon was standing right next to when introducing the restaurant as the location that they needed to be at by 6:30 to win the reward. I think that Craig, Nicole and Bobby had decided that they needed to wander in the direction of the restaurant because they didn't want to miss the time deadline if they were able to find clothes (or to send Nicole and Bobby with clothes to get $10,000 into the pot, even if they couldn't find big pants for Craig). They were walking down one of the two roads that happens to intersect right in front of the restaurant, and the producers had taken the laundry to the same laundrymat close to the restaurant. I don't think that they knew the clothes were there for sure, but that they were taking a logical approach of getting close to their destination.