I have read of many lawsuits against Lyft/Uber from passengers who were sexually assaulted by the driver, but have not seen any about the driver being assaulted by the passenger, I have a hard time believing this is the first case. Is it because the company is only liable for the drivers actions (even though they are independent contractors, not employees) but hold no liability for the passengers actions?
Passengers aren't screened so drivers (just like taxi drivers, EMT drivers, bus drivers, pizza delivery drivers, etc) face some risk.
Lyft does not permit drivers to carry weapons but Uber permits drivers to carry pepper spray and non lethal weapons. Lyft has an emergency number for drivers to call, but advise calling 911 first. Uber has an in-app emergency button that calls 911. Uber also has a "share trip feature" which can allow someone known to passenger and driver to follow the drive.
But you are not in a risk free job. If you have problems with a passenger, call the police.