Nobby
Welcome to the forum, you might want to have a look at the following FAQ which explain where everything is
Welcome to Benefits and Work I'm afraid it's quite unlikely that she will get a home assessment without a letter from her GP explaining why she cannot attend at the Assessment Providers offices.
Make your request in the Additional Information section at the end of the form.
There is very little difference between a home assessment and one done in the AP's offices, with the obvious exception that a home assessment is an acceptance by the AP that she has significant problems, although this does not mean an award is guaranteed.
Gordon