Is the money received by the wife's father from an investor who sells a security device to the governmental electricity company considered a bribe, whether he is a partner of the investor or not, and is it permissible to accept gifts from him if his money is from a bribe?

There is no objection to your wife's father agreeing with the device owner to market and promote it within his company, and to receive payment for that, provided that there is no deception or fraud in the marketing, and that this work does not affect his official working hours at the company. It is preferable that he inform his employer to avoid suspicions. However, if bringing in the device is part of his job, then he is not permitted to receive additional payment except with the company's permission. As for accepting his gift, there is no objection to it, even if his money is mixed.