Or 1) She realised they weren't around. There was nothing deliberate that she did to ensure they weren't around. If there was, please point it out.
2) Or yes, she forgot they were with them. If Roy can fail to realise that 2 clerics - one of whom was his best friend - were missing on a small outcropping, then it's entirely within the realm of possibility that the old lady forgot about the two recent arrivals to the group when focused entirely on protecting the only living family she has.No way she could forget they even existed.
Again, she also forgot her staff in the rush.