I'm shocked to see this much traffic on the topic without mention of Google killing their free unlimited storage for Google Photos.
Yes, it sucks to have to cover 'in the event I fall over' topics. In reality it should be at least 2 since she may pass at the same time.
For your family sake, having a clue where to look for is really helpful. As the designated photographer, you are most likely in possession of the most important images of other peoples lives. The images that would be a slide show for a future wedding, birthday or life celebration. An external drive is great because you can either plug it in & access data, with no skills. Online accounts become more involved, especially if timing hits & the subscription renewal fails & X amount of time has passed.
Using a password manager with an Emergency Kit can save a lot of work later on.