During an inquest into the death earlier this year the Oxleas NHS Foundation Trust, which oversees Green Parks House, said Mrs Mager's death "could not have been predicted or prevented".
But after court proceedings were served, the Trust admitted liability, saying they should have prevented her death.
More top news
Police investigating the Grenfell Tower fire have "reasonable grounds" to suspect corporate manslaughter may have been committed.
Charlie Gard will "inevitably" die shortly after being moved to a hospice and having life-support treatment withdrawn.
The service has 1,366 people rammed into a dozen carriages designed for just 640.