I'm not a comic book expert, but the flash is able to time travel. In the Flashpoint paradox, flash goes back in time and saves his mom... which of course leads to all kinds of timeline issues. I also believe there may be timelines where she is alive.... but once again, I could be incorrect. I found the comic funny, because it points out that there is a ridiculous number of superheroes with back stories involving their parents death. It seems to be one of the main ingredients when creating a super hero.
Doesn't Superman still have his Earth (Adoptive) mum? I suppose there's like a few you still have a family of any kind, but the problem properly comes down to the the fact that family means certain obligations for the hero, a task of which most writers things too mundane to give their hero. It's just an easy loop whole to get around a lot of different other issues as well.
Edit: Oh I think Shazam (Captain Marvel) still lives with his parents nope orphan, and possibly one of the blue beetles.
I believe so.... not sure about the comics, but in the cartoons she is alive. That's true... plus the whole tragic beginnings angle. Batman's character is completely built upon his tragic past.
As for the Mother's Day thing, I think they overdo it with orphan heroes. One of the many flaws of the Green Lantern movie. There was no reason to give Hal Jordan a tragic loss of his parents (though I think he's orphaned in the comics). GL and Flash are fairly happy-go-lucky for superheroes so they don't need to be chewing on angst burgers like most other supers. Wonder Woman's mom is usually alive in versions of her story arcs, though her relationship with her mom is sometimes strained.
That's true. She looks to be the exception to the rule, though I'm sure there are many others that I can't think of right now.