There are caregiver agencies that have 'sitters', caregivers who come in and whose sole purpose is to sit with someone. These agencies also offer more advanced care but if you just need a 'sitter' most agencies can accommodate you. When I say 'sitter' I don't mean babysitter but someone who comes in to sit with someone because they need some supervision.
I used to work for an agency called Home Instead. It's a national chain. If you google them or "home health aide", probably all the other agencies will start spamming and you can find someone local. Also try your local council on aging.
Most agencies have reviews that are separate from the agency website. Check out the reviews to make sure you get a reputable agency. Be specific when you contact them, tell them exactly what you need and what you don't need. If you think your mom might respond better to someone who's a little older, let the agency know that as well. I am a home healthcare nurse who works for an agency and somtimes our clients prefer someone with more 'experience'. The agency should work with you to get someone in the home who is a good fit not just for your mom but for you as well. Good luck! :-)
Good luck!