I am seeking temporary live-in or night time assistance for my Mom. Where do I start?

My mom is 91 and moved in with my husband and me in November following the death of my dad. My husband and I will celebrate our 25th wedding anniversary in October; to celebrate, we would like to do a cruise in January, which would take us away from home for about 3 weeks. I am seeking someone qualified to stay with my mom from perhaps 4:00 pm until around 9:00 am. Mom is reasonably independent other than driving; she would probably need to go once or twice to the grocery. Otherwise, we just don't want her to be alone during the night. The person would have the use of the master bed and bath, TV, and kitchen facilities. Does anyone know who I could contact in the Corpus Christi, TX, area?