1,261. Exemption from Mitzvos

196:2 An onen is exempt from all mitzvos, even if he doesn't need to deal with the funeral arrangements, such as if others are taking care of things for him. Even if he wants to be strict on this, he is not permitted to be lenient out of respect for the deceased. The onen may not recite any brachos, not even HaMotzi or bentching (grace after meals). If he is eating with others who are bentching, he does not respond "amen." The onen is not counted in a zimmun (a quorum of three for bentching) or in a minyan.

Negative commandments, however, remain prohibited to him - even those of rabbinic origin.  Therefore, if he wants to eat bread, he must ritually wash his hands but he may not recite  the bracha over washing, just as he doesn't recite the bracha over the bread. Similarly, when washing his hands upon arising in the morning, he washes each hand three times as per usual but he doesn't recite the bracha.

196:3 If the onen ate before the burial and, afterwards, the food was still not digested, he should bentch. Also, if he used the facilities before the burial, he should recite "asher yatzar" afterwards.