We are a very successful Immigration Law firm.
Based on the information provided, we charge only $1100/- for initial processing
Please contact
https://www.ranchodlaw.com/

Looking forward to assisting you.

Do it yourself. Look at the forums if you have no idea. $1100 is a lot of money for this successful firm. If a regular guy who can read and write and do it. I have done it myself. Save your money.

To do it myself, I feel risky because my father stayed in Nepal more than 2 years last time and came back in 2015.
Airport Immigration asked him to fill out the DHS form I-193 ( waiver of visa/passport) and Approved it on the spot and let him enter on the same Legal Permanent Resident (LPR) status.

Has anybody gone through this situation ? Is it risky to renew GC by myself ?

Thank you very very much for your advice.

I don't think there will be any risk on the particular situation. USCIS will approve your father's case for the renewal. In the worst scenario, if something unexpected happen, then you will get the RFE from USCIS, then you can proceed as per that letter and then if the case looks complicated then you can hire an attorney

However, I personally suggest not to invest a big bulk of money for the lawyer for this sort of work.

***Only my personal suggestion ****