In my humble view:
1. Your client is not eligible to opt for composition scheme u/s 10 (1) of the CGST Act, 2017 due to restrictions by clause (a) of sub-section (2) of Section 10.
2. Your client is eligible to opt for composition scheme u/s 10 (2A) of the CGST Act, 2017.
3. If option under above Para 2 is chosen, your client needs to taxes @ 6% (i.e. 3% +3%) against management Consultancy services of ₹ 5 Lac. However, this is subject to the presumption that this supply took place after exhausting limit of 20 Lac aggregate turnover from exempt supply by way by way of renting of residential property.
3A. If option under above Para 2 is chosen and in my personal view, your client need not pay taxes @ 6% (i.e. 3% +3%) against exempt turnover of ₹ 30 lakhs by way of renting of residential property.
All above are strictly my personal views and same should be construed as professional advice / suggestion.