Narrated Abu Sa'id: The women requested the Prophet, "Please fix a day for us." So the Prophet preached to them and said, "A woman whose three children died would be screened from the Hell Fire by them," Hearing that, a woman asked, "If two died?" The Prophet replied, "Even two (would screen her from the (Hell) Fire. "They said, “And one?” He said, “[Even] the miscarried child will certainly drag its mother [and father] with its umbilical cord to Paradise!”
Even Prophet Mohammed PBUH lost his daughter. Loss of your child is something toughest and most terrible thing parents can suffer. In this time of grief n pain only your strong faith in Allah and support from your near n dears can help.
Death is inevitable and its with everyone. I have my friend, my uncle n aunt n even my own parents gone thru this loss. Allah gives sabar to the family.
If husband n wife r healthy and they are together , inshAllah more kids will come. I know at this time it will be difficult for them to take it but time is best healer and they ll accept the loss slowly inshAllah.