The trick is to remember that the vast majority of corn snake genes are recessive. Thus, a snake needs to have *2* copies of a particular gene to show the trait.
A bloodred is homozygous diffused. Thus, it absolutely *must* give 1 diffused gene. So, if both parents are homozygous (having 2 copies of) the diffused gene, then all the offspring will have 2 diffused genes, and thus be bloodreds.
Snows are homozygous for amelanism and anery. Thus, the snow parent will contribute 1 amelanism gene, and 1 anerythristic gene. The bloodred parent will provide 1 diffused gene.
Because none of them match up, the offspring will all be normals that are het (heterozygous, meaning carrying 1 copy and not showing the trait) for amel, anery, and diffused.