In the part labeled “ a scary memory” through research I’ve determined to pass this one needs 150 (Blue Rose Corolla which it is nearly impossible to obtain that much. 150 Blue rose Corolla was sent in a package during the event but after it’s not the case. How should I get past this obstacle rather than over a year o gathering

They can be bought from gift vendors or found in Elion's Traces chests.

They reduced the amount needed for the story quest. They changed it to 50 Blue Rose Corolla instead of 150. You can buy them from Gift NPC in every town. Try farming to Chaos Zone to get Chaos Loot Chest, they sometimes give Blue Rose Corolla. 

I saw the postings that it was 150 of the flowers, spent weeks stopping at the gift shop every chance I had and it took weeks to collect 150, then I turned in the quest and it was only 50 that was required.

 

Getting 50 is easy (compared to 150) just stop by the gift shops consistently as they reset every 60 minutes, farm for Chaos Loot Chests in South Valencia which also drops them.