The best option is 4. Napping Neptune
Napping Neptune travels at an average speed of 120 Km/h. It will cover the 620 Km in 5 hours and 10 minutes, arriving at Hicksburg at 23:40. The passengers will have enough time to make their connections.
There is no cost for this option.
Option 1 will result in the passengers arriving after midnight. It takes Jumbo Jupiter 2 hours 4 minutes to travel 620 Km. With the 4 hour delay caused by the repair, the passengers will arrive at 00:34. The cost will be $8,000 for the train fare compensation and $30,000 for hotel costs.
Option 3 will also arrive in time for the connections. The repair delay added to the travel time will result in Jumbo Jupiter arriving at 22:04. This option will cost $12,000 for the new motor.
Option 2 will cost $16,000 for reimbursement of train fares. In addition, you fail to transport any passengers to their destination.