Hi Wendi,
 There are two things going on in the picture you sent. The gray-green and yellow structures are lichens. Liches are a mutually beneficial relationship between fungi and algae or fungi and bacteria. They grow on trees, rocks, fences, and other structures and are not considered harmful to the tree.
The off-white mushrooms are another story. They look like one of the sap rot fruiting bodies, but I can't say for sure which one without seeing them in person. That branch could be dying due to the rot, but it may not mean that the whole tree is going to die.
My best advice is to have the tree examined by a certified arborist to determine if it is structurally sound.
You can find certified arborists who work in your area at https://www.treesaregood.org/findanarborist
Type in your country (ISA is international) and your zip code, and the site will give you a list of arborists.
Best regards,
Sandy