How did it end?

Allie was being treated for cancer but was told the treatment wasn't working so she withdrew from the chemotherapy.

After her last appointment with her doctor she sees Gavin sitting over at a cafe waiting for her, she smiles and shouts "Guess what!?". Gavin looks at her with a "what?" look on his face. She looks both ways and starts to walk across the road, a bus passes in front of her blocking her from Gavin's sight. You hear car tires screech and a crash, Gavin's face drops as the bus passes and sees her lying on the pavement.
She was knocked down and killed by a van driver who said she deliberately stepped in front of him. This causes tension and anger among her family who are torn between thinking Allie did it on purpose, concluding that her treatment wasn't working. At her funeral they continue to argue and Brawdie (her mother) declares she was a coward for taking the "easy option". Her doctor is among the mourners and states that her prognosis was good and she had decided to resume treatment. The family now have closure, Brawdie and Gavin fall to pieces realising they had believed the van driver's word and had resented Allie during what should have been a sad and mournful time.
Darcey (who is pregnant by Eugine) takes Allie's place as head of the Hairdressing Academy, the family all toast to new beginnings and a bright future for the academy, the series ends.

Hope this helps.