Suggest me best/cheap plan for mobile recharge.

Futureized

Skilled
I have to recharge my vodafone plan (on my 2nd sim which is mostly disabled, primary sim is jio always active)

Usage:
Require mostly for receiving sms or call bank from registered number.
Calling last done 3 months ago

Make upi transactions
Banking apps
Finance apps
At max 50 mb days used per month
 
Your requirements are not relevant anymore. You must follow telcos requirements now. That is recharging with 198 rupees plan in case of voda. Because that's their lowest which offers outgoing SMS and all the basic shits.
 
If you need the extra SIM just for the sake of receiving OTP etc. and you do not need to make any calls from it, then just port it to JIO, because you can keep a JIO sim for many months without doing any recharge and it will continue to work perfectly fine for receiving OTP and phone calls etc. Unlike Vodafone, in which you will not even receive the OTP's if you do not recharge.