Starting with Bob, his mother is only mentioned a handful of times. No real explanation other than hints that she passed away when Bob was young, thus him having to work in the restaurant with Big Bob all the time. S5 E6 Father of the Bob and S7 E7 The Last Gingerbread House on the Left.
Then there is Jimmy Jr., Andy and Ollie's mom? No one ever mentions her. The only one time I can recall was when Jimmy Jr was doing his "musomes", S7 E8 Ex Mach Tina, he mentions her in them. Well, and there was that one time Andy and Ollie said "What does she mean came out of our mom?", S4 E2 Fort Night.
We know litte about Zeke's home like, other than he "moves around a lot". S3 E12 Broadcast Wagstaff School News. Also in S7 E20 Mom, Lies and Videotape, Zeke give a shout out to him stepmom Cheryl. We have also meet his cousin, S3 E21 Boyz 4 Now, Kevin and his Grandmother in S5 E8 Midday Run.
Regular Sized Rudy Stieblitz, we know he spends every other weekend with his Dad, S4 E15 Kids Rob A Train. And we have seen his father in several episodes but never his mom. S6 E12 Stand by Gene, he mentions that Tina looks like his mom when shes tired. She must live in the same general area since Rudy attends Wagstaff Middle School. Also appears in S6 E11 House for 1000 Bounces and S8 E18 As I Walk Through the Valley of the Shadow of Ramps and he was mentioned in S9 E10 Better, Off Sled.
Courtney Wheeler, we meet her dad, Doug, a few times also, but never her mom? S3 E8 The Underbearable like-likeness of Gene, S5 E1 Work Hard or Dye Trying, Girl, S6 E7 The Gene and Courtney Show, and S9 E8 Roller? I Hardly Knew Her!
Daryl, S8 E14 The Trouble with Doubles, he references calling his mom to come pick him up?