The increased demands for indoor wireless data services with the limited available radio frequency (RF) spectrum are motivating researchers to investigate alternative technologies to augment the existing RF networks. Utilizing the visible light spectrum by exploiting visible light communication (VLC) has shown strong potential to augment RF networks in indoor scenarios. The ubiquity of the power-line network makes it an attractive choice as a communication medium between the data sources and the VLC transmitters through power line communication (PLC). Hence, integrating VLC and PLC systems can be a strong complementary hybrid wireline/wireless technology for indoor data networks. In this paper, we investigate the power allocation problem for a communication scenario in which data is transferred through a cascaded PLC/VLC channel in parallel to an RF wireless channel. We develop an algorithm for allocating the transmission powers among the communication nodes to maximize the achievable rate. Our results show that the proposed system provides appreciable rate gains compared to conventional RF communication systems for the same amount of total transmission power.