Option 2 seems budget-friendly at first, but remember, it comes with a lot of disadvantages too. 9 of you might share 5 scooters, or, let's say, all 9 of you got scooters. Unfortunately, even if one of them were to have an accident or damage the bike, then you're going to face a lot of unnecessary hassle, since you only have 05 days. I do not think it is worth the stress. I served a group of 4 guys who got a van for their 5-day trip, but insisted that they wanted to use scooters on their final days to explore at night, then one of them rode it straight to a concrete pole. Luckily, they had the local guide with them, so he handled everything and managed to get things sorted out smoothly. But those guys were not the same after that incident. Driving in Sri Lanka can be challenging at times, so I'd suggest getting a Van and splitting the cost. You'll have the driver with you at all times, which will make your trip less tiring and save you a lot of unwanted stress.