I would like to send Dad to a day care for daily activities but he does better if my Mom is with him. Is that ok?

Have Mom go with him. She can slowly move away from him as he gets acclimated.

Does your mom want to go?

Can they both afford to go?

I think your parents can do whatever they want in this situation. If your dad would feel more comfortable with your mom there and she wants to go then they should do it.