Yes, I firmly believe God continues to answer the prayers of His people even after He has taken them to heaven.
Do you remember Hannah in the Old Testament? She prayed repeatedly for a son, and when Samuel was finally born to her, she then prayed that he would serve God all his life (see 1 Samuel 1:28). God answered that prayer, and Samuel became one of the greatest men of the Old Testament. He died as an old man, but he was faithful to the end just as Hannah had prayed he would be.
Never forget that God isn't bound by time the way we are. We see only the present moment; God sees everything. We see only part of what He is doing; He sees it all. The Bible says, "Before the mountains were born or you brought forth the earth and the world, from everlasting to everlasting you are God" (Psalm 90:2). Long after you and I are gone, God will still be at work and many of the things we prayed for will finally come to pass.
Yes, when we pray and nothing seems to happen, it's easy for us to think God has forgotten us, or He hasn't heard our prayers. But God doesn't always work on our schedule! He knows what it best, and in His time He will answer every prayer according to His will. Continue to pray for your family, and for others as well not only that they will be happy and safe, but that they will give their lives to Christ and live for Him every day.