This is a small maple? Need to see the leaves more closely but the top hole is just fine as long as birds or squirrels are using it. Problem if there are insects. Plenty of cambium to support tree and that tree has already thickened its epidermis to protect itself. Is there moisture inside that hole? Wrap a wad of paper towels around the end of a stick using duct tape. This stick should be green and easily bent yet tough to break. Push down into that hole till it stops (let me know the depth) and leave it for an hour. Pull it out. How wet is that paper towel? Heck, if it is wet at all need to block the hole after drying it out...best done in the summer. Let's see if it is even wet.
Down below, scrape the mushrooms off completely. You will need to make a large circle around the base of your tree. Clear it out of all vegetation. Pull back the soil from the bark of the tree. A thin layer of fine bark would be fine on top of the soil. Is that landscape fabric at the bottom? Pull it up and get rid of it. If that stuff is installed anywhere else, I'll try to talk you into getting rid of all 'weed fabric'...ugh!
Usually beneath the canopy of a tree it should be dry. That is why I am thinking you've got automatic irrigation spraying beneath this tree.
I'd like to talk about your foundation/brick of your home and the soil in contact with your brick and why and how to fix that! Then I'd like to know more about your lawn, watering, fertilizing and mowing. I'll talk you into enlarging your plant beds after getting the soil removed from touching your brick. Please send answers and we'll try to help you hold onto the value of your home!
Do you have automatic watering? This tree looks like it is in your lawn, yes? Could you take a picture from the road of the entire tree?