What can be proof of close ties and or intent to live in the US for citizenship?
You must show that despite your lengthy absence you did not abandon your intent to live in the US. To provide that you did not abandon your permanent residency in the US, you must show close ties to the US. You can use evidence such as:
Property ownership in US
Car registration in US
Active Bank account in US
Living arrangements that you maintained during absence
Any temporary arrangements you may have made during your planned absence. For example, you may have placed your belongings in storage for some time.
Affidavits from family and friends confirming your trip was temporary even though it lasted so long
Tax returns for all years of your permanent residency
Store cards, credit cards etc.
Any other evidence of maintaining life and ties in the US