Answer:
Phenotypes: All Brown Hair Color and All Short Hair Length
Genotypes:
Homozygous dominant hair color and  homozygous dominant hair length: (BBSS, BBSS, BBSS, BBSS).
Homozygous dominant hair color and heterozygous hair length: (BBSs, BBSs, BBSs, BBSs) 
Heterozygous hair color and homozygous dominant hair length: (BbSS, BbSS, BbSS, BbSS)
Heterozygous hair colour and heterozygous hair length: (BbSs, BbSs, BbSs, BbSs)
Explanation:
Hair color :
B = dominant brown 
b = recessive white
Hair length : 
S = dominant short
s = recessive long
 The dihybrid cross between parents with the genotypes: 
BBSS × BbSs
If BBSS self crossed; we have the following traits= BS, BS, BS, BS
If BbSs self crossed; we have the following traits= BS, Bs, bS, bs
The dihybrid cross is as follows:
               BS                     BS                  BS                BS
BS          BBSS                BBSS            BBSS             BBSS         
Bs          BBSs                 BBSs            BBSs              BBSs
bS          BbSS                BbSS           BbSS              BbSS
bs          BbSs                 BbSs            BbSs              BbSs
Phenotypes = All Brown Hair Color and All Short Hair Length
Genotypes include:
 Homozygous dominant hair color and  homozygous dominant hair length: (BBSS, BBSS, BBSS, BBSS).
Homozygous dominant hair color and heterozygous hair length: (BBSs, BBSs, BBSs, BBSs) 
Heterozygous hair color and homozygous dominant hair length: (BbSS, BbSS, BbSS, BbSS)
Heterozygous hair colour and heterozygous hair length: (BbSs, BbSs, BbSs, BbSs)