Want to know if i can file tax return. I only receive social security but in my credit karma app appears an amout to claim.

If the Social Security benefits is the Only income to be reported on the tax return and there is no federal income taxes being withheld, then there is no reason or need to file a tax return.

Unless you also received a Form 1095-A for your health insurance through one of the State Marketplace Exchanges or from healthcare.gov then you must file a tax return.

Unless you had tax withheld from your Social Security and need to seek a refund, you do not need to file a tax return if your only income was SS.   If you have a 1095A for marketplace health insurance you do need to file, in order to enter the 1095A.  Not sure what you think you are seeing on Credit Karma.