One resource is the National Family Caregiver Support Program (NFCSP), a federally funded program through the Older Americans Act. Services provided through this program include information for caregivers about more available services, respite care options, support groups, and even training.
For those with limited finances, you may want to look into your local Area Agency on Aging (AAA) to find out if there are any services you and your loved one are eligible for. The National Council on Aging has an online BenefitsCheckUp tool that allows you answer some questions and determine your mother's eligibility for various programs and help paying for medications, health care, food and more.