Providing access to home in case of emergency when I'm not there; Any suggestions?

Thank you all for your ideas. We live in city so our entrance is very exposed The idea of hiding box might work behind a pillar. I only want it as emergency as my husband collapsed suddenly a few weeks ago. I was lucky my neighbour was home and she is a key holder. He can be perfectly well and progress to collapse in an hour. Very worrying.
W.

Knoxbox. We had one put on my dad’s house. Local first responders are very familiar with it, they have access to opening it and it contains a housekey.

I was going to say Realtor box. Have one on Mom's house. Looks like they have people coming in from other Realtors.

You can install a small key box somewhere discrete on the exterior of your house--ours is on the side of the house and there’s a tree close by so anyone walking by never sees it. To open it, you enter the code using a combination-style keypad. But what I would actually recommend IF possible, is getting an exterior garage door opened. We have one too, it’s right outside the garage door and you enter a 4 digit code on the keypad and hit the up arrow and it opens. Of course this only works if you have a clear path through the garage into the house. You’ll also need to keep the door from the house to the garage unlocked. And like Barb said, when calling 911 give them the code and tell them where to find the keypad!

You get a "realtor box" that contains a key. You give the code when you call 911.