See in the eligibility criteria for EWS its clearly states that:

• The total annual incomes must not exceed Rs. 8 Lakh
• The residential area must be less than 100 Square Yards, residential flat must be less than 1000 sq.ft & agricultural land less than 5 acres.

Now as your grandfather has a plot of >1000 sq.ft and as you live with him i.e., he belongs to your family then you will not be eligible for EWS cetification.

I hope this answer helps. All the very best for your future endeavors!