80D or 80DDB

Medical expenditure can be claimed under 80D
For claiming exemption under 80DDB percentage of illness can be ascertained maximum limit under 80DDB is 100000 rupees

For medical expenditure of sevior disease deduction is allowed under section 80ddb for the medical expenditure incurred for dependents..

here is the some important part of section..

Deduction under section 80DDB is allowed for medical treatment of a dependant who is suffering from a specified disease ( if disease is covered under the section).

a. Can be claimed by an Individual or HUF

b. Allowed to Resident Indians

c. When taxpayer has spent money on treatment of the dependant

d. Dependant shall mean spouse, children, parents and siblings

e. In case the dependant is insured and some payment is also received from an insurer or reimbursed from an employer, such insurance or reimbursement received shall be subtracted from the deduction.

so as per the section you can claim deduction under section 80ddb for the medical expenditure incurred for your senior citizen mother up to rupees 100000.