I don't see why your mom wants to become an Indian citizen. This will especially be the case if Ukraine becomes a part of the EU ina few years.
IMHO, a better option is for your mom to get an OCI/PIO card. The OCI is essentially a lifelong visa to live and work in India without any restrictions. The PIO is valid for 15 years and also requires holders to register at the FRRO station if they stay in India for over 6 months. If you don't travel abroad much, this requirement should not be that taxing.