As someone who has worked with a LOT of 98+% sulfuric acid, I can offer a few suggestions:
Do NOT add base to it directly. It might well explode due to the heat released.
DO add it to water, very slowly. To dilute sulfuric acid safely, you need alot of water. You also need to pour it extremly slowly, depending on the amount of water. Even better: pour it onto ice. Sulfuric acid generates a TON of heat when you mix it with water. If you dump the thing in the water is going to get extremly hot extremly quickly. You need to add the bottle maybe over the course of 15-40 minutes to a bathtub full of water, keep checking the temperature.
On that note, do NOT use a plastic bucket or something to dilute it. The plastic bucket may well deform and collapse under the heat and pressure. I've had pyrex explode because acid was added too fast to the water. Again, adding it to ice is the safest since ice is cold so it can help counter the temperature increase.
After the acid has been diluted to a low concentration you can add alittle bit of base to it at a time to neutralize it. However, you don't have to if you keep diluting it. Highly dilute sulfuric acid is reasonable to dispose of.
Hey, you know what, it's winter. Go use some snow, if it snows where you are. And do it outside! You will get fumes from this process, especially so if want to add base but you will still get fumes just from adding the acid to the water.
If at all possible, dispose in a hazardous waste facility. Always. And don't forget protective gear! Long sleeve clothing, close toed shoes, splash protection (face shield, at least goggles). And don't wear nice clothes, I have holes in various t-shirts that I now wear to the gym because the last button on my lab coat wasn't done up and I leaned against a fume hood.