If it's okay I'd like to turn your question around...what did/do you need from your kids?
I never feel like I am doing enough for my mom! We lost my father 6 months before my sister so me and my family are all my mom has left. I try and inclued her in everything that we do and spend as much time with her as I can. We offered to have her move in with us but she is not ready for that yet...(she is only 60 and in great shape and health)
It's really hard to know what the right thing to do is, what will help...I guess some days nothing will.
I am so,so sorry for your loss.
I'm glad your girls are doing okay. I have 2 step-daughters who are 10 and 7. In 4 years they lost their birth mom, their step-grandpa, step aunt and step cousin to be(my sister was pregnant). It scared me SO MUCH that they were functioning so well after all of this loss. I couldn't understand why they weren't falling apart. I think as adults we expect kids to react to loss in the same way that we do but they don't-they react in their own way. Just letting your girls know that you are there if ever they need you is more than enough!