My father (89) keeps repeating to go to his house although he is home. He denies the reality and gets angry.

Continued:
What to do if they refuse to let go of the idea
Sometimes, your older adult will refuse to let go of the idea of going home, no matter how much you try to soothe

If that happens, you might need to agree to take them home and then go for a brief car ride.
Experiment with how long it takes before you can take them home without protest. Or, suggest a stop at the ice cream shop, drugstore, or grocery store to distract and redirect.
If it’s not possible to actually take them out or get into the car, even going through the actions of getting ready to leave can still be soothing. This will shows that you agree with them and are helping to achieve their goal.
Meanwhile, the activities of getting ready give you more chances to distract and redirect to something else.
Keep in mind that not everything you try will work the first time. And even if something works once, it might not work the next time. Do your best to stay calm, flexible, and creative – this technique gets easier with practice.

Also, it's always a good idea to play music when an elder gets agitated. It normally has a very calming effect on them.

With women, sometimes giving them a baby doll to hold & coddle helps A LOT. It's something they can remember, something they can relate to, and something to do that feels constructive and motherly.

Best of luck! I hope some of these techniques work!

Here is some useful info I found on the subject:

Why someone with dementia asks to go home
Alzheimer’s and dementia damage the brain and cause a person to experience the world in different ways. 
So, what we hear as “I want to go home” is often a request for comfort rather than literally asking to go somewhere.
The kindest thing to do is to meet them where they are, focus on comfort and reassurance, and respond to the emotions behind their request. The goal is to reduce your older adult’s anxiety or fear so they can let go of the idea.
Helping them to calm down also gives you a chance to check if discomfort, pain, or a physical need is causing this behavior.
 
3 kind, calming ways to respond to “I want to go home”
These suggestions will put you on the right track, but it’s a good idea to get creative and come up with responses that are tailored for your older adult’s history, personality, and preferences.
1. Reassure and comfort​ to validate their needs
Sometimes saying “I want to go home” is how your older adult tells you they’re tense, anxious, scared, or in need of extra comfort. 
By responding in a calm and positive manner, you’ll validate their needs and feelings. This helps them feel understood and supported.
Approach your older adult with a calm, soothing, and relaxed manner. If you remain calm, it often helps them calm down too.
If they like hugs, this is a good time for one. Others may prefer gentle touching or stroking on their arm or shoulder or simply having you sit with them.
Another way of giving extra comfort and reassurance is to give them a soothing blanket, therapy doll, or stuffed animal.

2. Avoid reasoning and explanations
Trying to use reason and logic isn’t recommended when someone has a brain disease. It will only make them more insistent, agitated, and upset.
Don’t try to explain that they’re in their own home, assisted living is now their home, or they moved in with you 3 years ago.
They won’t be able to process that information and will feel like you’re not listening, you don’t care, or that you’re stopping them from doing something that’s important to them.

3. Validate, redirect, and distract
Being able to redirect and distract is an effective dementia care technique. It’s a skill that improves with practice, so don’t feel discouraged if the first few attempts don’t work perfectly.
First, agree and validate
Agree by saying something like “Ok, we’ll go soon.” or “That’s a good idea. We’ll go as soon as I clean up these dishes.” This calms the situation because you’re not telling them they’re wrong.
Next, redirect and distract
After agreeing, subtly redirect their attention. This redirection should lead into pleasant and distracting activities that take their minds away from wanting to go home.
For example, you could gently take their elbow while saying “Ok, we’ll go soon” and walk down the hall together to a big window or to the kitchen. Point out some of the beautiful birds and flowers outside or offer a snack or drink they like. Later, casually shift to another activity that’s part of their daily routine.
Another example is saying “Ok, let’s get your sweater so you won’t be cold when we go outside.” Then, while you’re both walking to get the sweater and chatting about something pleasant, stop for a cup of tea or get involved in an activity they enjoy.
Or, ask them to tell you about their home. After a while, guide the conversation to a neutral topic.
Asking about their home validates their feelings, encourages them to share positive memories, and distracts them from their original goal of going home. Open questions that encourage them to share their thoughts work well.
For example:
Your home sounds lovely, tell me more about it.
What’s the first thing you’re going to do when you get home?
What is your favorite room of the house?

 

I have read in this forum posted by others with first-hand experience that their LOs are referring to the childhood home. This makes total sense. Those with experience will soon post lots of great advice for you. Peace!