Horizontal Control Word Format is
||Control Signal Field
Nothing is mention in question about Branch condition.
so number of bits for Branch Condition = 0
Same with flag, number of bits for flags = 0
Control field indicates the control signal which is 125 Control Signal.Since Horizontal control Word uses decode binary format to represent control signal i.e. 1 bit per control signal.
So number of bits required for Control Signal Field = 125 bits
Given Number of Instruction = 150 and number of cycle/instruction = 8
So total number of cycle required in 150 instructions = 150 * 8 = 1200 cycle
In Control Unit 1 micro operation require 1 cycle so total number of micro operation = 1200 micro operation
1 micro operation require 1 Control Memory Word Storage.
So total size of control memory = 1200 Control Memory Word
number of bits required to represent Control Memory Address = Ceil( log2 1200 ) = 11 bits
Minimum Size of Control Word = 0 + 0 + 125 + 11 =136 bits
** Control Word Size is not always mandatory to be multiple of 8. Actually there is no need of specifying bit or bytes in this question.