1. Bus: From Nanniwan, you can take the local bus to Yan 'an City, and then change to the bus to Hukou Waterfall at Yan 'an Bus Station. Specific trains and shifts can be consulted at the local bus station, which takes about 2-3 hours.

2. Long-distance bus: You can take a long-distance bus directly from Nanniwan to Hukou Waterfall, but the frequency is less. Need to check the quantity and frequency in advance, it takes about 3-4 hours to drive.

3. Charter car: You can also rent a car or charter a car locally, which is more flexible, but the cost is higher.

Regarding accommodation, you can choose a hotel or inn near Hukou Waterfall, or you can live in Yan 'an city. The results show that there are many accommodation choices and reasonable prices in Yan 'an city, while the accommodation conditions around Hukou Waterfall are relatively simple, but they are close to the scenic spot.

Generally speaking, there are many modes of transportation from Nanniwan to Hukou Waterfall of the Yellow River. You can choose the appropriate mode of transportation according to your personal needs and time. If you have enough time, you can arrange a 1-2-day trip to learn more about local culture and customs.