How do I respond to a neighbor with dementia when she is confused?

I have 2 neighbors with dementia. One has just been hospitalised after becoming violent with me so I have some breathing space whilst he is being assessed. He was angry because I stopped him from climbing over a high fence. He's 90 and frail. He's frustrated at me essentially saying he can't make a decision himself but it was very unsafe. My other neighbor is lovely and has carers visit 3 times per day. But she is straight out her door if she hears me, wanting to know what I'm doing. Sometimes we can have a good chat. As the day progresses she forgets me and asks if I've just moved in, or tells me to keep out of her shed. Yesterday she spent two hrs outside dressed to go out and waiting for her son who wasn't coming. When she's like this is it better if I just agree that I've just moved in? Should I try to make her understand he isn't coming? Today she's in and out hanging up then taking down the same towel on the line. She's always on the go and thin as a rake but repeating tasks seems to calm her. Any tips on how to react to odd behaviour or aggression would be helpful. As a non family member I only know what I see but want to do my best to keep an eye out for them without intruding.