This is, I think, a very telling point in this sorry story.
There may be some of you who have been privy to the reaction of near family members to grievous and unexpected loss.
It is an overwhelming grief that blots out any motivation for action, and IMO beginning legal proceedings to sue for damages is a vanishingly small concern until much later in the grieving process.
Unless those closest to the deceased are persuaded by others, perhaps those with a strong interest in the financial outcomes of suing, who have taken advantage of the mother’s helplessness to stake a claim.
I have no legal training, but common sense suggests that this latter point could figure strongly and even convincingly in the case for the defence.
I’m not being unkind, just realistic.