Amazon Home Cleaning Services, available on Amazon, from $20 per hour
The house will be messy. The parents will be tired. Though a clean, organized environment both feels great and is easier to navigate, they probably won't have the energy for it with a newborn. You'll want to coordinate with them beforehand, but this is one of the most thoughtful gifts you can give.
Though prices and availability vary by area, you should be able to book a cleaning professional to do any type of service around the home (including a deep clean) at around $20 per hour.