Is that where the footbridge crosses the River Dyfi? I don't think its been mentioned that the trackbed of a disused narrow-guage railway runs from right outside the cottage that MB rented down to this bridge. Most of it is below the level of the road, from which it cannot be seen.
I'm afraid that if the body April was thrown into the Dyfi from that bridge, it could easily have been swept out to sea as the river is running in full flood after the weeks of heavy rain we have been having.
Perhaps MB was walking along the river the next day to ensure that she had disappeared from sight?