given such a common surname, there could be other Daniel & Lizzie O'Briens in the area, but they showed up in the city you mentioned for births of the children - though it might be worth checking out.
The occupation for this Daniel seems to be 'moulder'
Was it in one of the 'Dakota' states (i.e. North or South) that your Daniel died ?
Seems to be quite a distance away from Philly...
There also seems to be various counties, towns and cities named Dakota.
S.