Ann said to me, “ Are you working tomorrow?”
Convert into indirect speech.

Option a ‘Ann asked me if i used to be working the subsequent day’ indicates the proper use of the above-given rules, as we will see the employment of past imperfect tense and that we can even use ‘if’ to hitch the 2 clauses. Hence, it's the proper option.
Option b ‘Ann asked me whether i used to be working the following day’ also indicates the acceptable use of the above-given rules, as we will see the utilization of past progressive and ‘whether’ which is employed to affix two clauses. Hence, it's the proper option.
Option c ‘Ann told me that i used to be working the subsequent day’ denotes the incorrect use of the reporting verb ‘told’, as we only use ‘asked’ in interrogative indirect speech. Hence, it's an incorrect option.
Option d ‘Ann said to me that you simply are working the subsequent day’ indicates the utilization of present imperfect tense and therefore the inappropriate pronoun ‘you’. Hence, it's an incorrect option.
The correct answer is Option ‘a’ and ‘b’.