Sec 44AD is for computing PGBP on a presumptive basis. An eligible assessee(i.e., any resident individual, HUF or firm, but not a LLP) who has not claimed any deduction u/s 10A, 10AA, 10B, 10BA or 80HH to 80RRB & carries on any eligible business is eligible to pay tax on a presumptive basis.
So there is no restriction on claiming deduction u/s 80C