Pedigree - Dealing With Unknown Parent Genotypes
Based on the information given in the pedigree, you can actually be certain that #2's mate has a genotype of CdCa because of the following:
Two of 5's siblings are albinos. Since albino is a recessive trait (lowest in hierarchy of dominance), both parents (4 and 4's mate) must have the Ca allele. Let's call 4's mate "8". Since 8 has the Ca allele, at least one of 8's parents must also have the Ca allele. Since you have already (correctly) determined that #2 is CCk, #2's mate must have the Ca allele, and must therefore have a genotype of CdCa. 

Thus you can eliminate the extra (1/2) from your calculation, making the answer (1/2) * (1/2) * (1/4), or (1/16).