BB/Bb = orange tail
bb = blue tail
Muffy's mom has a blue tail but Muffy has an orange tail. Therefore, Muffy carries a heterozygous genotype Bb.
Muffy's mate has a blue tail like her mom. He carries a homozygous genotype bb.
If Bb is crossed with bb, the offspring will have a 50% chance to have an orange tail or blue tail.
ANSWER: Muffy's offspring has a 50% chance to have a blue tail.