Just because your mom lives far away doesn't mean she can't be in a family photo. You can paste it using software such as Adobe Photoshop Elements or any version of Adobe.
Step 1. Open a digital image of the person you want to add to the photo (in this case, mom)
The greater the contrast between her and her original background, the better.
Step 2. Use the selection tool to select the head and body of the mom
This tool will highlight one or two dots to help blend Mom into her new environment.
Step 3. Copy the selection to a new layer
Step 4. Open the photo you want to add mom to
Drag the layer containing her cutout shape onto your family portrait. This will automatically create a new layer in this file.
Step 5. Select the move tool and use it to place mom on the photo, wherever you want
Resize if necessary with the Free Transform Tool.
Step 6. Adjust the lighting so that mom does not stand out from the rest of the family
Select the mom's layer and adjust the exposure. To keep it from standing out, place something in front of it. Select another family member and place him in the foreground so that mom is, say, behind you.