Is it possible that her Mother or father was exposed to asbestos? She may have picked it up from her father (even before birth) or mother.
All patients I have nursed with a mesothelioma were men and men that had worked in some kind of dock lands work or painting/building work.
Working with certain paints in the 1940’sand working in the docks can expose to asbestos.
It is interesting that you mention about the hospital renovations as many old building s did contain asbestos.