Interest income from financing business

As per Explanation to Section 44AD

(a)  "eligible assessee" means,—

(i)    an individual, Hindu undivided family or a partnership firm, who is a resident, but not a LLP firm as defined under clause (n) of sub-section (1) of section 2 of the Limited Liability Partnership Act, 2008 (6 of 2009); and

(ii)   who has not claimed deduction under any of the section 10A, 10AA, 10B, 10BA or deduction under any provisions of Chapter VIA under the heading "C. - Deductions in respect of certain in-comes" in the relevant assessment year;

(b)  "eligible business" means,

(i)    any business except the business of plying, hiring or leasing goods carriages referred to in section 44AE and

(ii)   whose total turnover or gross receipts in the previous year does not exceed an amount of two crore rupees.

Hence, answer to your question is Yes, interest income from financing business of a Proprietor is included under Section 44AD.