Car Accident With Fatality — Can They Sue Driver?

My stepfather-in-law was hit by a DUI driver and is in critical condition. He was the one driving.

The other passenger in his car was a friend but also one of his workers. They were off hours. Unfortunately, he passed away from the injuries he sustained about an hour after the accident. We have contacted family that lives in another country.

Police are still investigating, and it’ll take a while due to the fatality and the suspected DUI. We know nothing about the other driver so far, except he had minor injuries and was taken into custody (and might be on bail).

It’s a complicated and heartbreaking situation, but now my mother-in-law is worried about talking to the family of the deceased because she’s scared they will sue the stepfather since he was the driver and he’s even the employer. Would they have grounds to do so, if the other driver is found completely guilty? (Aka the DUI driver ran a red light, which we suspect.)

I’m torn because I want to help the family who’s mourning and obviously so does my MIL, but everyone’s talking in her ear saying she needs to protect herself.

TL;DR: Can the family of the deceased sue the driver of the car he was in, even if the other driver is at fault for the accident?