With chaos surrounding Annalise, she just can’t stand the pressure anymore and needs to escape. Meanwhile, Frank must come to terms with the things he has done while Wes continues to get closer to finding out about his past.
Part of the reason the Season 2 finale took place at Annalise's mother'shouse is because of the demand for Cicely Tyson's return (the actress who plays Ophelia). Nowalk claims the question of when Tyson would come back was one of the most asked questions from the first season: "For me, it was just figuring out a real reason why she would return, but also, we're literally just working on Cicely's schedule." Once they found out Tyson's available dates were around the time of the finale, this triggered the idea of taking the finale out of Philadelphia.
Although he had no idea how Davis would deliver the "he needs to go" line, which Annalise says to Bonnie, Nowalk insists she "did it perfectly". It's yet to be revealed whether Annalise meant murdering Frank, but the line was purposely written to be ambiguous.
The writers weren't 100% sure that Caleb would be the murderer of his parents because Nowalk feared it would be "too obvious". "That is something we went back and forth with a million times and it just felt like the best answer as we came up to it."