I agree with your last paragraph as a probable reality. A complicated scenario for such a small result.
This certainly seems an example of @Hal_Al's 'implied life estate'. She Quit Claimed in 1994 but lived out her life in the house until 2003. She likely maintained the costs of the home until that time even though my youngest brother was living there as well.
There are no public records of any transaction in 2003, with the next transaction being our purchase of the 1/3rd chare in 2004.
