I agree that the Rider A drop-off to Rider B pick-up is deductible, but I still think the trip to and from your home is questionable. The IRS clearly says that merely doing business at home (such as logging into Uber) does not make it a business location for deductible miles.
The tricky part with Uber is to define where the 'business location' starts. The first pick-up or the arrival to a 'busy area' would definitely be a 'business location', but just logging into Uber from home would not necessarily make it a business location (unless your home qualifies as your "Principal Place of Business").
