No, it's not possible at all. Matlab does not have pointers and there is no mechanism to access slices of a matrix (even read-only) that does not involve making a copy of that slice.
You could indeed create a separate handle class that would store the rows of the matrix but you don't need to do that as long as B doesn't need to modify the array in A. Instead you could store your rows in a cell array in A. You can then pass (by value) these rows to B. As long as B does not modify these row, due to the copy-on-write mechanism of matlab, you'll be in effect passing pointers to the rows. However, as soon as B tries to modify a row, you'll initiate a copy of that row. In fact, if B doesn't modify the array in A, you could just pass the whole array to each B with no memory overhead. Actual copying only occurs when the copy is modified.
If B does need to modify the array, then you'd have to go the way of your separate C class. That's going to create a fair bit of overhead. Personally,instead I'd create an interface in A only accessible to B so that B can query/update the array in A whenever it needs.
