Way to Kedarnath is opened from May to October only. From November to May You usу must use helicopter . Be careful , from May to November its quite hot in New Delhi, were the road starts.
From New Delhi bus station buses go to Haridwar almost every half an hour. Road takes 8 hours. Also you can go by train, this will take 4-6 hours.
From Haridwar you can go directly to Kedarnath but it is also possible to stay there at least one day - this beautiful city is placed on Ganga.
If your group is more then 5-6 persons you may think about renting a jeep. This will cost around $20 per person. Bus is much cheaper ($5) but slower.
Way to Kedarnath goes through Rishikesh, Devaprayag, Rudraprayag and ends in Gaurikund. If jeep goes fast it can reach Gaurikund in 9-10 hours. Please note that road from Rishikesh to Gaurikund will be closed from 8 o'clock in the evening.
Himalayas start near Rishikesh (half an hour from Haridwar). All the road to Devaprayag goes near Ganga. In Devaprayag Bhagirathi (Ganga) and Alaknandu unite. Very beautiful place! We recommend to stop here and at least to put your legs into this holy water.. After Devaprayag road goes alongside Alaknandu to Rudraplayag, were Mahaalaknandu and Mandakini rivers unite. After Rudraprayag road goes alongside Mandakini.
It is highly recommended to stay overnight in Gaurikund. It is placed in 2 km above the sea level. This is not very high but it is better to start getting used to low oxygen level. There are two Gauri svayambhus in Gaurikund: two spring sources. One with hot water one with yellow water. It is not possible to go by car to Kedarnath. But you can rent a horse for 400 rupees ($8). 14 km road you can go in 4-5 hours. It is possible to go by foot but it is quite hard. There are a lot of hotels in Kedarnath from 100 to 300 rupees in a day. There is no hot water but you can order it for 20 rupees.