There are many different types of non-Hodgkin lymphoma. Some grow very slowly, often needing no treatment for months or even years, whilst others are much more rapidly growing and aggressive and need very active treatment with strong chemotherapy.
There are very few medical reports of women who have become pregnant after treatment for non-Hodgkin lymphoma. This may be because often the drugs needed to treat the condition will reduce fertility or even lead to sterility. However in the few reports there have been of pregnancy after treatment for a non-Hodgkin lymphoma there is no evidence that a future pregnancy increases the risk of the cancer coming back. Nor is there any evidence that the previous treatment leads to any increased risk of damage, such as birth defects, to any future children.
Some doctors do advise waiting a couple of years after finishing treatment in order to have as good an idea as possible about what the long term outcome of treatment is going to be.
The best thing is for your daughter to have a chat with her specialist and they will be able to advise her what is best in her particular situation.

