The extra $2.7B for OAS was mandated by law from ages ago, neither Trudeau or Harper made any change to that so it would have happened regardless.  That one is a simple mathematical formula.

The $4.2B extra in children's benefits is "good" I suppose, though again some of that increase was purely due to population change and inflation.  Under Harper's plan the increase probably would have been about $1B to $2B, so really Trudeau's change was only $2-3B or so.

As for the Conservatives, they did go from a $13.8B surplus in 2005/06 to a $5.8B deficit in 2008/09, but by my count that is 3 years, not two.  Further during that time income taxes were cut (by Martin, but the impact showed up on Harper's balance sheet) with the bottom bracket going from 16% to 15% and the GST was cut from 7% to 5%, saving Canadians a good $15B or so.  Also some of that $5.8B deficit was due to the recession which started halfway through the 2008/09 fiscal year.