It was a mod where you would find a key for 'your home' inside an ayleid ruin. so it was seamingless integrated into the game. Does anyone know the name?

There are quite a few house mods that have Keys that you have to find or quest for. I think I used one by Princess Stomper that did just this.

https://princessstomper.wordpress.com/2009/05/02/silorn-manor/

The sites like Oblivion Real Estate that let you search for Houses based on if they had a quest related to them or not are not up anymore, so that does not help either.

http://www.nexusmods.com/oblivion/mods/searchresults/?src_cat=68

There are so, so many house mods out there....literally hundreds. Can you give any other specific details about the mod? Such as where is the house located? What type of home was it? Any special features that would help identify it?