What transportation can you suggest we take going to garden hotel from Guangzhou airport?

Well, you haev two choices at that time.
1. take airprot shuttle bus line 1 to the railway station, and then take a taxi to reach the hotel. The taxi would cost around CNY25. The bus operates till the arrival of the last flight, so you can surely catch it.
2. If taking taxi directly, it would cost around CNY130 to reach Garden Hotel.