In it has been a combination of standard MREs and the Humanitarian version of the MREs called HDR (Humanitarian Daily Ration). You will more then likely get the HDRs which are basically vegan (no animal products) and have no heater. These are typically in a Pink or Yellow package similar to the MRE packaging and contain around 2200 calories... They are pretty much horrible, worse then the current menu of MREs.

Other agencies will have other meals and food stuffs and when they setup shelters they will more then likely provide hot meals as soon as they are able to. There are some caterers that are setup specifically to support emergency incidents that travel around supporting disasters and fires that have some pretty good food (especially considering the quantities they produce).