If I arrive Hongkong Airport, how to go Ovolo West Kowloon hotel by Airport Express.

Upon landing, you can take airport express to get to HK Station.
The ticket fare is 100 HKD per person. It takes around 24 mins on the way.
After arriving, walk west along Middle Queen's Road around 0.9 miles. Then you can find the hotel easily.

Is any bus service available to reach Ovolo West kowloon.?
Which will be more economical to take taxi or airport express or Bus for 3 Adult + 1Kid.
Regards

It is most economical to take shuttle bus line S1 + Tung Chung MTR line to Nam Cheong first. Then walk eastwards to your hotel in around 5min. It costs 16.8HKD per person. Well, for the sake of your kid and suppose you carry many luggages, taxi shall be a good choice. It costs 200-220HKD.