E.,
My aunt became a single mother when her husband left when their daughter was two. My aunt spoiled my cousin rotten. We thought it was because she felt guilty, but I think it's just her personality. Her daughter grew up to be a very sweet girl, but she still has little respect for her mother. That probably won't change until she has children of her own.
Now my aunt is re-married and has a 4-year-old boy. Her son is just as spoiled rotten as her daughter was. I should also mention that my aunt is a very intelligent, educated woman. It's true that toddlers go through these phases, but sometimes they get away with too much. You can tell because the children behave with other people, but not with their own parents. My aunt is very sensitive and she is more concerned about hurting her son's feelings than she is about teaching him to have manners. We all made excuses for her when he was 2 and 3, but he'll be 5 in Feb and he still bosses her around and cries at every little thing and tells her not to laugh. He has difficulty getting along with other kids at pre-school because he is so sensitive. It's partly his personality, but his mother has catered to this behavior, thus reinforcing it.
My mother tried talking to her sister about it, but she became very defensive and it caused them to have a rift in their relationship. So I guess my advice is just to be careful about this topic. He may grow out of it. He may become a holy terror. It's hard to tell at this age.
If you decide to share your concern with your friend, try to do it in the most diplomatic way you can imagine. Try to think of how you would feel if someone called your parenting skills or Sophia's behavior into question. Maybe you could just tell her that you know his behavior is normal, but it drives you crazy. Try to equate her situation to your own and tell her it makes you dread when Sophia will be that age. Maybe even ask her for advice on how to prepare for it...just to get the conversation started, not sounding like you're attacking her but that you respect her.
Okay, so I'm no expert, but that's how I approach my aunt and I'm the only one she really talks to about this stuff. Of course you know your friend best. I hope this helps. Sorry for being so long-winded.
Good luck!
-T.