yes if its general housekeeping duties,it depends upon a lot of factors, your relationship with client, if you do them one favour at no extra cost ,eg defrost fridge then NExt week will they be wanting laundry doing as part of the norm also?
Its your call but it works out at over £10 ph so you are making an ok profit despite also having to pay your mum the other 2 hrs.Do they supply the cleaning products?if they supply products I would say its an ok price.