Two helpless aged ones, and two little nieces to took care on, and nobody but himself to earn the money to do it with.
The little nieces' Pa had gone to California after his wife's death--and hadn't been hearn from sence.

The little children had been left with their grandparents and Uncle Tom to stay till their Pa got back.

And as he didn't git back, of course they kept on a-stayin', and had to be took care on.

They wuz bright little creeters, and the very apples of their eyes.

But they cost money, and they cost love, and Tom had to give it, for they lost what little property they had about this time--and the feeble Grandma couldn't do much, and the Grandpa died not long after the eppisode I am about to relate.
So it all devolved onto Tom.