No she isn't responsible and it's a complete insult to suggest otherwise. What effort was she have to made?
We have agencies in place who are tasked with investigating, sharing information and protecting the public. Meghan did not work for any of these agencies. She was assured by the Met, the letter containing concerns would be dealt with. It was their responsibility then to act on it and share if appropriate with the relevant authorities.
If these agencies have not done what they were meant to do, then they need to be held to account and investigations need to be carried out IF processes were not followed. There is absolutey no legal process that would find Meghan in anyway responsible for the abuse of children.