So sorry to hear about your mom.
There's no harm in applying for the DTC. If your mom qualifies, it may open up other doors for provincial programs so there's nothing to lose.
There are certain caps associated with claiming both the disability amount and nursing home medical expenses. CRA has a great chart that breaks down the situation: https://www.canada.ca/en/revenue-agency/services/forms-publications/publications/rc4065/medical-expe...
