travel the same day of submitting my application

hi everyone

my wife mom is ill and she has to travel today at 1800 to her country, we are ready to pay the fee and submit her Citizenship application online today!
i wonder if she is allowed to submit the same day she leave UK and book an appointment which she will attend after her return to UK (2 weeks time),many thanks

Yes fine.

thank you for your reply,we followed your advise and we did apply on the same day she was leaving UK(12/03/2019)
now we have to upload her current passport which we already have it on the computer(she applied with it for ILR last month) but without the last trip stumps on her passport or we need to upload her current passport with stumps on her passport for last trip(from 12/03/2019 to 18/03/2019)?
and also we couldn't figure it out which category we shall put the referees any help will be highly appreciate,many thanks.