These are not OBE's or even lucid dreams, but rather, just dreams. I say "just" dreams, but they're more like "special" dreams in that they were a combination of special things that can occur in dreams, such as a visitation and a gift of insight as to what happens after one passes. At least, that is what this sounds like to me. When you have an OBE, more often than not, you're conscious of leaving your body, know where your body is at and go where you wish to go. This doesn't seem to be the case here. I suspect that with receiving your mother's ashes, you were thinking of her a great deal, or certainly more than you have been and she paid you a visit in the form a pure energy (the orb) and then showed you what she experienced after passing. That is why you went through a tunnel to the tree and the waterfall. I also suspect that you will dream more often now as it sounds like your Mother came to give you a special gift in the form of opening your energy and expanding your inner sight.