Whenever Mrs. Rossini would come over, it seemed like Mona couldn't refrain from making some snide remark towards her. Maybe I'm missing something, but their rivalry (if you want to call that) really came ahead in the episode "Chose Me" from Season 7, where Mona and Mrs. Rossini are competing for the affections of the same man.

Granted, when Mrs. Rossini came over to talk about her husband, Joe, leaving her, Mona was very supportive. So the women appeared to actually get along really well to an extent. And Carmella dished it out as much as she took it from Mona..

That's such an interesting observation because in hindsight you're right - why would she be that way with Mrs. Rossini without any prior history? Funny thing though, my mom (Italian immigrant, very close to Mrs. Rossini actually!) was highly amused at Mona taking pot shots at her. I wonder if back then the more upper class hoity toity types of Connecticut would automatically look down on Italians from the city. Maybe it was something that would resonate with both groups, but my mom never found it insulting, she would laugh hard "with" the jokes... and of course laugh harder when Rossini gave a side eye/snide comeback!