What can I do to a small space between my garage and house?(walkway)

Do you have any stepping stones or blocks there now?

small stone then add some larger walking path stones

You might find some ideas here. While I used small walkways in the search box, some of these are not small but take a look. You might get some ideas.

https://www.google.com/search?q=decorate+small+walkway+between+buildings&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi7ybzg3dfVAhUV3YMKHc2qA00Q_AUICigB&biw=1200&bih=604

Good luck!

curve a walk using pavers and coloured stone...plant appropriate (to your zone and light conditions) shrubs or plants around the edges ...perhaps an arch with a fast growing vine

Mine is like a tunnel, a wind tunnel so I have a dutch door on one end, and its covered, so I hang my ladders and extra fencing in that space on the wall with L-shaped shelf braces. I store the hoses in there wound in large flower pots.

Right now hosta plants and shrubs are on clearance being the season is wining down along with flower pots and if they are not the right color then spray paint them. Here are a few pictures to landscape that narrow pathway.

I would use pavers next to the garage or the house and then plant the space on one side with plants that will do well in the shade as it's like shady in that area since the buildings are close together. Some vining plants do well in shady areas so you could have vines go vertical up one of the walls to make the area more pleasant. Your County Extension Agent could advise about plants that would thrive in your area.