If they are receiving Social Security Retirement Benefits or Social Security Disability the support that you provide will not affect them since they are entitled to these benefits based on their Earnings History.
If your parents are receiving SSI and they do not report the support that you provide they can lose their benefits and even risk having to pay them back. SSI is a needs-based entitlement that is determined by all income and support.
Additionally you should confirm that you parents qualify as your dependents. Click on the answer link below for details regarding the dependent qualification of your parents.
https://ttlc.intuit.com/replies/5694100