Number of contol words = 256*1 = 256 (Each instruction has 1 micro operation).
Number of address lines = $\log{256}$ = 8
3 bits for flag and number of bts for control signals = $\log 48$ = 6.
No. of bits in each control word = 8+3+6 = 17.
Size of control memory = $\frac{256*17}{8}$ = 544 B.