Where can I find an agency who can stay with my mother for a week while I visit my father who has dementia in a home?

If your Mom won’t leave the house, an in-home agency can do 24 hour care. Just google ones in you local area. I chose one that was only a few blocks from my Mom, and they hired local caregivers. My thought was that there would be fewer excuses for tardiness or absences if they were quite local. It worked out mostly. It should be easier since you only need 1 week. There will probably be a 3 different caregivers, but the agency will schedule them and bring them to meet you and Mom in advance after an agency nurse does an assessment. Be prepared for the sticker-shock.

It would probably be a lot easier to take her to an AL or skilled nursibf facility for a respite stay. You would have to hire multiple people to come stay with her for a week.

We placed my Dad in a local AL while we needed a break, lots of them have "respite care" for a week or more, and may be cheaper than in home care. He thought he was in hotel, and actually enjoyed it!