From the AZA care manual for meerkats, mongoose, and Fossa:
Meerkat: One facility housed meerkats and rock hyrax together for several years. While there was some aggression at first (biting on the part of both species) it eventually calmed down. Important to the success of this combination was: 1) making sure that both species had their own nest boxes, 2) making the door of the meerkat box too small for the hyraxes to get in, because they would fight over the box, and 3) hanging the hyraxes' diet in areas that were too steep for the meerkats to climb to prevent them from eating the food (J. Greathouse, personal communication, 2003).
Meerkats and dik dik have been housed together with no challenges reported. Aardvark and meerkats have been exhibited together; however, meerkat aggression towards the aardvark was reported over food and space. With time, these conflicts resolved themselves when the aardvark learned to avoid the meerkats. Meerkats have also been exhibited successfully with African crested porcupines (pregnant porcupines should be removed prior to giving birth as meerkats will kill offspring) (K. Kimble, personal communication, 2004 & 2005).
Other combinations reported include: guenons and banded mongoose; meerkat, yellow mongoose, fennec fox, and Cape ground squirrel; meerkat, zebra, lechwe, and porcupine; meerkat and yellow mongoose; meerkat and giraffe (one meerkat was lost to trampling by a giraffe); and narrow striped mongoose with jumping rats (Muir, 2003; C. Brown, personal communication, 2006).
Apparently mixing of banded mongoose and primates has been done before. Not with meerkats. The manual doesn’t note the hornbill mixed exhibits.