More important evidence would be of you:
1) Paying US taxes. As LPR you need to file taxes on wordwide income. Did you do it all these years? If yes, download tax return transcripts from IRS website and print out.
2) Did you maintain any bank accounts, brokerage accounts, any other assets in the US? Bring proof of all that.
3) Do you have a job lined up? Do you have a lease or any solid evidence you're coming for good?
You can and should bring evidence of taking care of mother, but more importantly you need evidence of ties to the US.
If questioned about it, stay positive, kind and do everything to assure you're coming to the US for good.
Also, if lucky to reenter, I'd stay in the US until you naturalize if you can. Which would be 5 years from entry.