Surgery followed by adjuvant chemotherapy is a reliable therapy for colon cancer, but is associated with side effects and risks. Recent advancements in nanobioengineering in the form of targeted nanoparticles, cubosomes, liposomes, nanosheets, nanorods, quantum dots have generated substantial advancements in theranostics of colon cancer decreasing the cytotoxic drugs' side effects. We describe a facile mechanism of preparation of hybrid nanocomposite encompassing Au and Ag. Preparation of hybrid nanocomposite is one step process which may be easily escalated. The nanocomposite was characterized using transmission eleactron microscopy, energy dispersive X-Ray spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infra-red spectroscopy, UV-Vis spectroscopy, photoluminescence and cytotoxic studies. In-vivo studies were carried out in Balb/c mice. Photothermal heating experiments in HeLa cells were promising and the characterization studies clearly indicated the formation of hybrid nanocomposite. In-vivo experiments confirmed the efficacy of treatment, along with involvement of epigenetic regulation, which may be helpful in translation from research to clinical applications.