
Asuming neither have any problems anyway they should be fine. Two youngesters will be a bit more work for you mum for sure while you are away but I am sure as long as she is aware of this she will manage. A baby gate sometimes comes in handy at these times.
Tolieting training may lapse a bit but they will be good company for each other.
As you have a couple of weeks let your puppy go up to your mums for a couple of hours to ensure all is well and your mum is coping OK.