Parent renting half of duplex for free, does it make income a wash for rental property?

Apt A:
Renter is paying $600 a month for a 2bed/1bath and is well below fair market value

 

Apt. B:
My mother lives here as her primary/only home rent-free

 

So on my income taxes when I go to declare income is it $0?

 

Thanks for any info. on this!