You can plan to visit & explore Hampi in October, as this is Dusherra month it will be festive there. Minimum three days are required to explore Hampi fully. Get a hotel near Virupaksha temple in the old Hampi. You can also plan to stay across the river Tungabhadra for one day to explore the other side. There are so many cool places to visit and you will definitely need a two wheeler to roam around. If you have any questions feel free to ask. Hope it helped!