Reminiscence Of The Past is a quest offered by Ricky, the bartender and de facto proprietor of the Phoenix Inn in the Great Market district of Aleroth during the events of Divinity II: Flames of Vengeance.
Ricky tells you that his mother's amulet (Eleanor's Necklace) has sentimental value and he believes that it protects him from harm. He'd like to get it back, but unfortunately Henry and Eleanor's House is in the Crow's Nest district, and due to the infestation of walking dead he cannot. He'd like you to retrieve it for him.
If you have not yet done so, you'll need to complete the quest Bark up the Right Tree to gain access to the city's Crow's Nest district. Henry and Eleanor's House is in the northwest area of the district, across the road from Servus and Alina's House and the Sewer Tunnels entrance. Be prepared to face level 39 and 40 ghouls, hell spawn, and skeletons within. Also beware of the pressure plate floor traps throughout the house.
Once inside, you'll notice that the house seems to be in a state of disrepair, and has quite a few corpses strewn about. Proceed a short distance north to an intersection, where you'll see two bandits fleeing the undead. Head west at the intersection, then north to a large room with several beds, dealing with the traps and undead along the way. There are three regular chests here (containing random loot), plus a small chest on a table that contains your objective: Eleanor's Necklace.
If you'd like to thoroughly loot the remainder of the house, refer to the Henry and Eleanor's House article. Otherwise, return to Ricky at your convenience to complete the quest.
Note: You can give the necklace to Astridax on Lanilor Lane to complete the "An Amulet for Astridax" sub-quest of Sinister Motives. This rewards 6211 exp, 1300 gold, 1 skill book, and two choices. The quests are mutually exclusive - you cannot complete both.