Answer
Maximum size of memory unit: $16$ MB
Dimensions of memory: $4096\times 4096$
Work Step by Step
There are 12 bits for row so there will be $2^{12} = 4096$ rows, similarly there are 12 bits for column so there will be $2^{12} = 4096$ columns.
The number of addresses will be $4096\times 4096$ and each address stores 1 byte so the maximum capacity of the memory will be $4096\times 4096$ bytes$ = 16$ MB.
