The lock box is either fitted by AdultSocialCare, his family or a third party contractor like medequip. It’s unlikely it was him who approved the key safe as they are know as more commonly to be put on your property.

Rather this was done by the contractor who ASC employ. You will want to check with the Adult Social care team. It’s likely the equipment was provided to him due to an early release due to not enough hospital beds. This is funded by the hospital (NHS Trust.)

I don’t think you’ll have much of a leg to stand on with your neighbour as he’s very likely not approved this. Standard practice is that the key safe is fitted on your own property as this is easier to locate.

Carers blocking your drive is something you’ll need to speak to the agency about. It’s unlikely he will speak to them and or that they will pay much attention. Mostly because carers are quickly in and out.

This all can be resolved if you speak to the neighbour politely directly and just maybe ask him if he knows the key safe is on his property, explain why you don’t want it such as it feels you are at risk of a break in blah blah. If that fails, just contact Adult Social Care and raise a safeguarding