Can we legally pay security guard before paying money to their agency?

We would need clarity on whether as per the engagement and the agreement terms with the Security Agency, the security guards get their salary paid via the Security agency or directly through the society?

It seems from the question that the salary of the Security guards was being paid by the Security Agency and if this is in line with the agreement with the Security Agency, we would suggest the Society not to pay the Security Guards directly as it would not meet the agreement terms and the Security Agency can seek its entire dues from the Society (including Security Guard Salaries). In such a scenario, the Society might end up paying double the amount - one on humanitarian grounds paying salary to the Security Guards directly and second on Legal Grounds in case the Security Agency bounds the Society Legally to the Agreement terms.

You may advise the Security Guards to approach the Security Agency for their dues and final salaries as the Security Agency is legally bound to pay their salaries. In case the Security Agency does not pay their dues they may issue a letter to the security agency at the first stage. There after they may issue a Legal notice, failing which they may approach labour authorities in this regards.