Sadly this is very, very common. As it's in the evening it could well be an example of "sundowning".
It could get better, but on the other hand, it could get worse and the demand to "go home" could increase.
It could be brought on by
1) Anxiety, which leads to a desire to "go home" ie a familiar place she associates with comfort and security
2) Your mother no longer recognises the place she lives in, and thus has reached the conclusion she needs to go "home"
3) Your mother remembers a place she used to live in and wants to go back there
4) A combination of any or all of these
A similar desire to see long-dead relatives such as a parent or spouse can occur, for the same reasons.
Unfortunately, I think this is an issue that most people with dementia exhibit at some time or other, and all you can do is to offer comfort and reassurance to ease the anxiety.
There is no point in pointing out your mother's error, she will not believe you and will not understand, which will upset both you and her. It might be possible to cook up a story about recently moving to her "new house", she might believe that, she might not.
If your mother has reached this stage then I think it is time for a care assessment because there is a fair chance that eventually your mother may start to wander from the "strange place" she finds herself in in order to "go home", particularly is she is living on her own.