I think Uber A is...
Mona! Mona Mona Mona... She has been it the whole time! Yes, she did lose it for a while but she took her spot back and wants to finish what she started! She took the blame off of her when she admitted to being A so it would look like she gave up that lifestyle BUT... If so many clues still point to her! Plus said by the end of the show we are going to come full circle and it will make sense.... This started with Mona and it will end being Mona.... Of course she isn't alone though... While she does have access to technology and is dirty... I think Caleb has been helping her the whole time! Did anyone else notice how weird it was that Caleb knew exactly how Mona liked her coffee in season 7? They have history! Caleb has the tools and knows how to do anything with any type of technology! We all know A is all about the technology.. From the trackers to the cell phones.. The computers..
Also Hanna was stupid when she left Mona in charge of watching Noel.... She also had a fake badge into Radley when Wren was there! Mona always disappears when bad things happen... Also I've noticed when Hanna tries to keep Caleb in the dark about her plans... A ends up messing up or getting surprised some way some how.... There is a reason why this whole series they have always showed Hanna trying to lie to Caleb or trying to keep things from Caleb... It's a clue! Caleb always wants to be in the know so he can hatch plans with Mona! Caleb even hired Sara H when he was doing his little biz... I don't think that is a coincidence.. Caleb knows how to set up these elaborate plans to catch "A" and they ALWAYS mess up... When he is involved in a huge part of a plan it always goes wrong.. He messes it up on purpose!