Anxiety generally comes from not knowing what is expected. Confidence comes from knowing what is expected.
If your dog is suffering with severe anxiety he/ she is unable to make decisions without becoming stressed. To help your dog at home what I would recommend is a minimum of a month of controlling everything he does so that you remove the stressful options from him. Basically tell him EXACTLY what is expected 24 hours a day.
There are two things that will really make it easier for you and your dog during this process.
1) crate training your dog if he/ she is not already crate trained
2) Teaching your dog the place command. This is where they are trained to stay on something with a boundary (pet cot, dog bed, blanket, rug).
Once you have taught your dog place you will find that this is your most used tool in helping with anxiety. If you are watching tv he should be in “place” watching it with you. If you are fixing dinner he should be in “place” keeping you company. If you are entertaining guest he should be in “place” hanging out with you.
If you are not around to tell him exactly what is expected have him in a crate so that he doesn’t have to figure it out himself.
Structured walks (walking at your side paying attention to you, not sniffing the ground or pulling) is super important as well. That is how you show your dog the world and teach them how to “view” it. Calm at you side means view the world calmly and trust your mom to show it to you. The calmer and more controlled his life is, the better he will understand how to react in it and how to relax in it.