Depending where you are and what you are after, a few ideas:
North Wales: If you take this route from the car park at Moel Arthur it shortens it. Tracks and bridleways, nothing ‘technical’. There are two big hills either side of Penycloddiau, but she can push up those. Nice views, quiet.
Rivington: Avoid the hills and pootle around the reservoir. If you are happy to push up one steep bit, take the bridleway from Yarrow Reservoir north up Lead Mines Clough and follow around the top of the reservoirs to Healey Nab woods, which has a few fun paths in it. If you do venture up to the Pike and Tower, don’t take upper track from the Tower to the north-eastern car park as it’s not for beginners (rocky road)! (e.g. do 1-9 and 16/17 here.)
+1 for Delamere, not hilly and she can spend some time going around the rooty bits as well as doing the fire roads.