As Mumbai is quite far from Agra where the Taj Mahal is located, it is not possible to do an overnight trip to the Taj Mahal from Mumbai. The quickest way to get to Agra from Mumbai is to take a flight to Delhi and then take a train or drive to Agra. Here's a sample itinerary for a 2-day Taj Mahal trip from Mumbai:

Day 1: Mumbai to Delhi

Take a morning flight from Mumbai to Delhi.
Upon arrival in Delhi, you will be picked up by a private car and driver and driven to your hotel.
Spend the rest of the day exploring Delhi on your own or with the help of a local guide.
Overnight stay in Delhi.

Day 2: Agra and Taj Mahal

After breakfast, your private car and driver will pick you up from your hotel and drive you to Agra (approximately 3-4 hours).
Upon arrival in Agra, visit the Taj Mahal, one of the Seven Wonders of the World, and explore the Agra Fort.
In the evening, drive back to Delhi and drop off at the airport for your return flight to Mumbai.
Note: It's important to check the opening hours of the Taj Mahal before planning your trip, as it is closed on Fridays. Also, the travel times mentioned above may vary depending on your mode of transportation and traffic conditions.