I guess, fully powered Nate Grey is the strongest one in the family. Vulcan is beyond Omega Level but I don't think he beats Nate.
Peter David did an alternate future in X-Factor that tied into the creation of Utopia. Scott was still around decades after he should have been dead from old age (thanks to cyborg parts) and Ruby was his daughter with Emma in that timeline. Emma wasn't there anymore, and I don't remember if it was even stated what happened to her.