There is no legal reason I can think of why such an adoption would be forbidden. Hence I would answer in the affirmative, Yes a hindu family can adopt a muslim girl.
I am unaware of any legal impediment to a Hindu family adopting a Muslim child and I would be surprised to discover the existance of any such impediment, but I strongly recommend that you consulkt with an attorney who specializes in adoption in California to get a clearer picture of this area. I am aware of certain traditional religious objections to such an arrangement, but these are, in my opinion, dying out and are typically rarely seen outsoide of rural areas of India. I suspect your question is better put to your priest and for an examination into the area(s) in which your child will be raised for purposes of consideration of the practical ramifications of this decision.
Yes. Being a member of one religion or another or one culture or another is not a prerequisite to adoption. If it is a healthy situation for the child, the court will likely approve. Good Luck
