Do I still need to guide my daughters in their homeworks or should I let them do it by themselves? My eldest is in grade 6 and my youngest is in grade 4.

Best to let them try on their own first so they can actually utilize or put to practice what they were taught in school. If they are really stumped, you can help out. My mom didn't help us with our homework but what she'd do is to check them when we were done --just to make sure we did the work and that everything looks good. Maybe you can do that, instead of guiding them along all the way.