If shop owner removes what can be done - no salary slip or bonus records?

Dear All, I need your help, My father working in private job (Shop Delhi) as a sales man for last 34 years with same owner. Till time my father age is 57 years.
Now my question is :-
If in future owner remove my father in our shop, so what can I do. last 34 years owner paid salary in cash.( No salary slip, no bonus, no gratuity)
We don’t have any proof in written please suggest. we are middle class people so I need your help .

Dear Sudhanshu,
Please note that, if your dad was working for a small shop and collecting an salary in cash with no written proof of the same then it is really very hard to prove the continuous employment. Also, as it is a small shop and if having employee strength below 20 then they are also not covered under ESIC or PF.

Thanks Mr. Kamble for your valuable reply
So please suggest what can i do for father. because my father has no extra earning in future .
Please guide with legal way. i had some witness in market its helpful or not.
I agree with you below 20 staff pf & Esic are not applicable .My father more than 30 years work with same owner, so any act on this.
Please advise for better answer.. thanks for your reply