There is no concept of uniform min wages across the entire country.
Instead, each state decides minimum wages, which are generally notified every 6 months. The notification is industry wise and for each skill level.
However, since you are in Maharashtra , the salary of security guards will also be governed by the wage rates specified by the guard board act. You can not pay less than the rates specified by the guard board even if minimum wages is lower.
Further, all statutory dues (PF, esic, cess to guard board) must be paid,
You also need to provide for gratuity that would be payable after 5 years of work.
In deciding security guard charges paid to security contractors, generally amounts are added for uniform, shoes, which are to be provided free of cost to the security guards. Further ensure you have factored in a reliever cost.
Please note that no security guard can be given a shift more than 8 hours as per law (12 hour shifts, though common, are illegal). 1 weekly off is required to be given for each security guard. If he works on weekly off, then a compensatory off in addition to double rate overtime is payable.