Mother wise I think Trish would be good. As long as Dante can see Trish as Trish instead of his mother. It stops being less weird the more you're around it and they've had time to adjust.
Lady would also work well. DMC3 showed they had some chemistry. I honestly see Virgil as the better dad though. Dante is tooooo overprotective. And rash. I think he knows he wouldn't be a good dad like that. Probably why he never had a kid. Nero smacked his ass after being treated like a little kid. So Dante's probably telling himself he'd be a lousy dad after that.