Yes, there will be 256 µ operations or 256 µ Instructions(Each instruction has 1 microoperation)Since the question is saying about vertical µ programming, So we need not generate 48 control signals at the same time, So we will use a decoder of 6 * 64 size which needs 6 bits for control signal field of a control word and since there are 8 flag conditions are used for condition checking, so we need MUX 8*1 using 3 select lines, we need 3 bits for storing this information in control word, Apart from this, since there are 256 micro Instructions present in control memory , so we need 8 bits for the next address field of a control word.
So the size of a control word = 6 + 3+ 8 = 17 bits
Size of control memory = Number of control words(Micro Instructions) * size of each control word
= 256 * 17 bits
= 544 Bytes