catering

hello,
one of our client is doing small canteen business. he has turnover Rs.20k per day which is around 60lac per annum. since it is an road side business he is not providing bills to his customers. whether he can opt composite scheme? If yes then what is the % of gst? and his wife is doing catering business. On which she earns around 15lac per annum. whether she needs to register under gst as they are relatives.