Nobody knows the full history of the reasons why this little boy was in his fathers care - all the reports state is that there was an argument before xmas and that was the last time she saw him - nobody knows what the contact arrangements or restrictions were. She may have had video calls with him at a pre arranged time over xmas, or this may not have been possible - but the full information is not there to blame this mother for not being in contact with the child.
All the people that are making out that he was incapable of caring for his own child because he was 60 years old are incredible - how many of these same people use grandparents age 60+ to care for their own children?
The Dad was in poor health but so are many other single parents with little to no support - I don't see posts stating that single mothers should not have care of their children, or the child's dad should be checking up on her all the time. Under normal circumstances this would be seen as controlling and invasive.
Sadly this Dad's health failed him and the poor child was left alone and passed in tragic circumstances, it cannot be the fault of anyone. The police should have carried out the welfare check on 2 Jan but there is no guarantee that this poor child would have still been alive then.
The social worker that found them must be going through hell, this is something that will stay with her for life, affect her career and decision making in the future and will impact on her mental health.
Tragic for all concerned - but not really predictable or preventable.