This is a new client  to my firm.  On his 2018 Tax Return  (prepared by a different firm) he claimed HOH  and took his mother as a dependent using a different address . (I suspect it is his mother's address) 

I am not sure how to file his 2019 tax return since the address information on his  license  was the same address of his sister (who is Head of Household).  

The taxpayer is not a dependent but  does not qualify for  2019 head of household. 

 I am very hesitate about preparing this return.  Help or suggesstions?

Can I file him as "Single" and can he claim his mother as a dependent ?