I would assign near 100% certainty that the little boy is Malik and that the photo was taken in 1959 just before BHO Sr. departed for the US.
The boy is the spitting image of the father. The mother and grandmother are in the photo. The boy looks to be a tiny toddler of about 1.5 years old to me, as he would have been in late 1959. Malik was born in March 1958, according to Wiki.
I see no indication or evidence that this toddler is any other child or that the photo was taken in any other time-frame.
That's 'granny' Sarah sitting next to her husband Onyango, the young girl standing is their daughter Zeituni, born in 1952. In 1964 she would have been 12 or so. Kezia isn't in the photo.
Omar was already in Boston, Zeituni went to live with the Kenyan and Ruth in Nairobi, 'Jane' we have no idea, Yusuf is the brother with whom he attended school at Maseno where Yusuf was known as Joseph and Sayid still lives in the village as 'granny' Sarah's shadow.