In this paper, a rectangular-shaped wideband dielectric resonator Graphene inspired electronic band gap (EBG) based complementary split ring resonator (CSRR) loaded miniaturized THz MIMO antenna is designed having a dimension of 56×56×3.6μm3 is designed on a Roggers RO3035 substrate with a relative permittivity of 3.6 and loss tangent 0.0015. This antenna works in the range of 6.0THz-12.5THz (70.76%) with a peak gain of 7.68 dBi. This composite DRA materials having Silicon (εr = 11.1) based cylindrical dielectric and cylindrical Graphene disk to be stacked on rectangular radiated antenna having height of 13.5µm and 0.2µm to improve the impedance bandwidth as well as gain of the antenna from 5.24dBi to 7.68dBi. Firstly single-element gold plated rectangular shaped antenna is transformed into a two-element MIMO antenna with mushroom-shaped EBG structure is deployed for improving the isolation between two antenna elements as well as to improve the front-to-back ratio (FBR). CSRR is loaded to obtained band notch characteristics for avoiding the interference between near wireless devices in the span of 10.6-10.8THz. Graphene disk having 3µm height put on Silicon (εr = 11.1) based cylindrical DRA provides high gain and improved the impedance bandwidth for achieving wide bandwidth from 6.0THz-12.5THz. The proposed MIMO Antenna performance has been judged by antenna parameters like gain, return loss, isolation between two antenna elements, diversity parameters like ECC, DG, TARC, Mean Effective Gain (MEG), Channel Capacity Loss (CCL) and found proposed DRA-MIMO antenna suitable for wide band nano/optical communication in 6G for IoT and bio-medical sensing application.