Take any document that proves social and financial ties to Canada.
You should have $100/day for the length of your visit to the US. They goal is to convince the consul that you have strong ties to return to Canada in a timely manner after your visit to the US.
Since you just returned from a 5 month plus visit to the US, I strongly advise you not to seek a fresh entry so soon. Taking into account that you now have a spouse who is an LPR, you are risking refusal of entry.
I am fairly confident her last visa refusal was due to 214(b). That in itself will not be held against her while adjudicating her fresh visa application, though her chances of not over coming 214(b) still stand.