Greetings from smoky California. I would advise your family to avoid both highway 89 and highway 50. 50 is closed and will not re-open any time soon as the Caldor fire has little to no containment. It's been burning for several weeks already and as of today is 19% contained. I-80 is open and would be the best route but you will drive right past Tahoe. That's fine because you can't even see the lake as the smoke has settled in like a dense fog. If that is their final destination, I would advise heading further north instead. Smoke is bad from north of Redding to Fresno so you've got to go to the Oregon border to avoid the dense smoke. Nevada near Reno and Carson City is just as bad as that's where most of the smoke is blowing.
To put things in perspective, the Dixie fire is the largest single source wildfire in CA history. As in forever recorded history.
The Eastern seaboard has hurricanes, the mid-west has tornadoes, the west has fires. It is a natural disaster area so plan accordingly.
2021 Fire Season Outlook | Welcome to CAL FIRE - Day to day updates on the major fires.