A) Get your dad to pick them up anyway. They're his grandchildren, after all.
B) Go pick them up yourself. They're your kids, after all.
C) Have a relative in the South Bay pick them up. They're family, after all.
D) Have your nephew drive 12.4 miles to the Oakland airport, 29.2 miles to Belmont (paying the $4 toll to cross the bridge), and 34.4 miles back home. They're his cousins, after all.
If you chose D, congratulations! You're qualified to be part of my family.