All are grammatical, yes.
The only thing I would change is to use "the" in front of "bathroom" instead of "a."
1. We can massage old people's backs.
2. We can help them use a computer.
3. We can visit their houses and clean rooms.
4. We can take them to a bathroom in wheelchairs.
5. We can help them wash their faces.
6. We can help them take a bath.
7. We can prepare towels and soap for them and help them take a bath.
8. We can help them walk to a bathroom and wash their bodies.
(Are the expressions above all grammatical? Would you check errors? Thank you.)
2 answers
7 and 8 seem repetitive. You said you can help them take a bath in 7 and help them wash their bodies in 8. That's really the same thing.