The five year old, whose case has made headlines this week, could be allowed to live on a long-term basis with her mother's mother after being withdrawn from foster care.
Judge Khatun Sapnara from East London Family Court said on Wednesday that social services staff at Tower Hamlets council considered the women a suitable carer. She wants to return to her country of origin.
The unnamed youngster, who is said to come from a family of Christian heritage, was previously placed with two Muslim foster families.
Judge Sapnara, who is herself a practising Muslim, decided the two placements were not culturally appropriate. She also emphasised the complex nature of the case.
Earlier this week, The Times reported claims by the youngster that she was not allowed to wear a necklace containing a cross and was stopped from eating bacon.
She has been allowed to return to her maternal grandmother on a short-term basis. A longer-term decision will be made after further analysis of evidence.
According to Judge Sapnara, the five year old was placed in foster care on an emergency basis in March this year after police exercised powers of protection.
The girl's mother is said to want to resume the care of her child as soon as possible. While she claimed her family had a Christian heritage, Judge Sapnara said there was evidence the women's parents had an Islamic background.
Judge Sapnara acknowledged that there had been no culturally matched foster placement available at the time. She said also social services staff disputed certain allegations which have arisen in the case.
The judge said the girl's mother had "raised some concerns" about the "appropriateness" of the placement but had not applied for a change of foster carer.
Judge Sapnara, who is due to reconsider the case at a hearing on 2nd October, said she would need to decide: whether the girl suffered - or was at risk of - significant harm; whether the youngster's mother could properly care for her; and whether other relatives could home her in Britain or abroad.