I guess you mean this link?
<a class="navbar-brand" href="https://wordpress.stackexchange.com/questions/325734/<?php site_url("home'); ?>">Homee</a>
Then I’m sure it won’t work on any other page than home. It’s because site_url() function doesn’t print anything – it returns its value.
And don’t print it either. That means, that the link above is empty 😉
You should change it to this:
<a class="navbar-brand" href="https://wordpress.stackexchange.com/questions/325734/<?php echo site_url("home'); ?>">Homee</a>
PS. Another thing really concerns me in your code. site_url('home') – it should be site_url('/home') (if your home URL is example.com/home) and site_url("https://wordpress.stackexchange.com/") (if your home URL is example.com/).