It sounds like the removal people they hired did a really sloppy job, came in and just removed the bees but did not remove the comb, etc. As beekeepers, we get calls to do honeybee removal, but will turn down the job if bees have already built comb in a structure in a hard to reach area. In that case we refer them to someone with the knowledge and tools to do a complete clean out that most often requires cutting out parts in the structure and rebuilding afterwards. Part of the responsibility lies on the homeowners to do regular maintenance inspections on their homes and be aware of any evidence of bees going in and out, if you catch it early before they build a lot of comb and store a lot of honey you can avoid the problem this lady had.
My husbands aunt who died left us her house. Bees had been going in and out of the bedroom wall for years (per the neighbor)through the electric meter. There were 80000 bees between the walls. We had a bee man come out and he used a vacuum to remove the bees which he took away plus many 5 gallon buckets of honey. He said that the recycled honey would be used to feed other hives and the queen would be used to start a new colony. Very interesting process. Hats off to the bees and the bee men and women.