I'm not saying A is a parent, but if it could be, who would be believable?
Pam: she would be my first choice. She was so regimented, conservative, and narrow-minded. I can't forget her need to have a 'perfect wholesome family' from the early seasons. She has come along way over the seasons, more accepting of things out of her control... but could that be an act? She never seemed fond of Emily's friends.
You don't have to attend every argument you are invited to.
"A" reads like a spiteful manipulator, so I'm leaning more toward a mom over a dad, but I honestly cant see any of the parents as A.....
If I had to try, I'd say Mona's mother. Mona learned that mess from somewhere.
Ella Montgomery.
I feel like she has the most to be angry about with the actual girls and could easily use the A facade to carry out her inner teen girl vengeance. She probably blames their influence of the girls on her daughter as the reason behind Aria dating Ezra, not to mention being mad at Aria for lying to her about Byron.
And, as a result, she probably looks down on her daughter's friends' parents and blames them for pretty much being terrible parents, which they definitely are, and raising bad kids - or else is jealous because she has a crap marriage and they don't.